tag:blogger.com,1999:blog-26594169698678661712024-03-18T09:48:06.221-07:00No TricksRisk, Security, Math, CryptoAnonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.comBlogger291125tag:blogger.com,1999:blog-2659416969867866171.post-8476841327348232342013-04-30T14:36:00.000-07:002013-04-30T14:37:08.595-07:00Some Mindmaps Online<div style="text-align: justify;">
Over the years I have developed many mind maps when writing articles, and I have also used them as a way of collecting information and organising it. I was a fan of <a href="http://freemind.sourceforge.net/wiki/index.php/Main_Page">Freemind</a>, and with effort, I uploaded some maps to the Freemind gallery. Later I switched to <a href="http://freeplane.sourceforge.net/wiki/index.php/Main_Page">Freeplane</a> but it still did not give me a simple way to share maps. I have now taken out a membership at <a href="https://www.mindmeister.com/">MindMeister</a> as the site can read and publish mind maps in a collection of formats. You can find about <a href="https://www.mindmeister.com/users/channel?title=Luke%20O'Connor&id=lukeo">20 or so maps here</a>, mainly from past articles, with new ones to follow. There is a large map on <a href="https://www.mindmeister.com/272765427/it-security-industry-2008-trends-and-analysis">Trends & Analysis</a> from 2008, giving you some idea how complex and from which sources you need to collect information to get a handle on IT Security.</div>
Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com68tag:blogger.com,1999:blog-2659416969867866171.post-42801913880745618202013-04-22T01:53:00.001-07:002013-05-01T05:16:19.493-07:00The 12 Bonk Rule<div style="text-align: justify;">
I am on a mailing list from Business Insider and against my better judgement (which often comes out when the internet is involved) I followed a link to an article on <a href="http://au.businessinsider.com/50-sexy-scientists-2013-2#49-cheska-burleson-1">The Sexiest Scientists Alive</a>. There are 50 scientists listed, and scientist number 43 is <a href="http://au.businessinsider.com/50-sexy-scientists-2013-2#7-clio-cresswell-43">Clio Cresswell</a>, a mathematician at the University of Sydney, who is the author of <a href="http://www.amazon.com/gp/product/1741141591/ref=as_li_ss_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=1741141591&linkCode=as2&tag=thebusiinsi-20">Mathematics and Sex</a>. </div>
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<a href="http://4.bp.blogspot.com/-5dsaDKAC6AA/UXR8G-O8HzI/AAAAAAAABps/bCvug1IoeCU/s1600/Screen+Shot+2013-04-22+at+9.52.54+AM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://4.bp.blogspot.com/-5dsaDKAC6AA/UXR8G-O8HzI/AAAAAAAABps/bCvug1IoeCU/s320/Screen+Shot+2013-04-22+at+9.52.54+AM.png" width="214" /></a></div>
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The book gained some notoriety for propounding the <a href="http://www.smh.com.au/lifestyle/life/blogs/ask-sam/the-12-bonk-theory-the-sex-you-should-have-before-settling-down-20101115-17tot.html">12-bonk rule</a>. Bonking is a term in Australia for having sex (usually casual sex as I recall), and Dr. Cresswell has stated that the best strategy for finding a good (sexual) partner is to bonk with 12 twelve different partners, note the best one, then keep bonking until you find someone who is better, then settle on that partner. You benchmark on a sample of 12 partners, discard them, then take the next best that comes along. Cresswell reports that this strategy gives you a 75% chance of finding a good mate. So it's not foolproof, but with the confidence of mathematics, it proclaims to be better than any other trial-and-error approach that leaves behind a trail of discarded lovers. Of course there is more at play in finding a mate than "bonkability", as opined in the <a href="http://www.smh.com.au/lifestyle/life/blogs/ask-sam/the-12-bonk-theory-the-sex-you-should-have-before-settling-down-20101115-17tot.html">Ask Sam column</a> of the Sydney Morning Herald for example.</div>
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The result caught my eye as I was recently reviewing some statistical problems and I surmised that the 12-bonk rule had a similar sounding result to the <a href="http://en.wikipedia.org/wiki/Secretary_problem">secretary problem</a>, a classic problem in probability. The secretary problem (which by now should be at least upgraded to the executive assistant problem, or simply just the candidate problem) asks for the best strategy to select a secretary for a position where there is a collection of candidates and you get to have one interview, upon which you must either hire the candidate or move onto the next one. It is assumed that the market is competitive and that you will not be able to return to a rejected candidate as they have found employment elsewhere. </div>
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The optimal strategy here is to interview 37% of the possible candidates, make a note of the best one, and then keep interviewing until you a find an additional candidate that is better than you previous best, and then choose the new best candidate as the one to employ. So if you have 100 candidates, interview the first 37, note the best, and then keep interviewing until you find someone better and then hire them. The <a href="http://www.math.uah.edu/stat/urn/Secretary.html">graph</a> below plots the probability of finding the best candidate using this strategy, as the percentage <i>k</i> of candidates interviewed and refused increases.<br />
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<a href="http://1.bp.blogspot.com/-88ufCUtYX-c/UXTVPO9C1bI/AAAAAAAACMk/AW-w7KJzpzA/s1600/Screen+Shot+2013-04-22+at+4.09.24+PM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="298" src="http://1.bp.blogspot.com/-88ufCUtYX-c/UXTVPO9C1bI/AAAAAAAACMk/AW-w7KJzpzA/s320/Screen+Shot+2013-04-22+at+4.09.24+PM.png" width="320" /></a></div>
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Here 37 is the double winner in that the point marked by the dashed lines indicates that the optimal approach is to reject the first 37% and then you will find the best candidate as the next best choice 37% of the time. This magic 37% is derived from <i>1/e</i> = 0.37, where <i><a href="http://en.wikipedia.org/wiki/E_(mathematical_constant)">e</a></i> is the base of the natural logarithms.<br />
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I just downloaded the e-book version of <a href="http://www.amazon.com/gp/product/1741141591/ref=as_li_ss_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=1741141591&linkCode=as2&tag=thebusiinsi-20">Mathematics and Sex</a> and took a quick look at the 12-bonk section, and it seems that Cresswell's discussion is based on the work of <a href="http://psych.indiana.edu/faculty/pmtodd.php">Peter Todd</a> in his paper <a href="http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.46.5283">Searching for the Next Best Mate</a>. Todd looks at simpler heuristics to find a mate than applying the 37% rule, which he notes has the following drawbacks in practice. If we assume a sample of 100 people where they can be rated uniquely on a scale from 1 to 100, then when applying the 37% rule<br />
<ol>
<li>On average, 37 additional people need to be interviewed (or bonked) to find the next best beyond the best found in the initial 37 people, for an average total of 74 people being considered from the 100.</li>
<li>On average, the best person found has rank 82, where 100 is the best on the scale. The 37% rule finds the best person 37% of the time, but averaging the success out over the remaining 63% of choices, lowers the result by about 20%.</li>
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Todd decided to explore other decision rules that performed better than the 37% rule on some criteria, and more closely match with our observed behaviours for finding a mate. It is unlikely that anyone will have the time and (emotional) energy to engage with 37% of all their potential mates, which could easily run into the thousands. Todd's computer models found that if you engaged 12 people from a mating population of 1000, then took the next best, you are highly likely to end up with someone in the top 25% of the population. I cannot quite tell from Todd's graph referring to this result as to how many people must be engaged in total, but seemingly around 30 or so (50 at the outside).</div>
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So this was the genesis of the 12-bonk rule, and I will read Crisswell's book a bit closer to see if she has teased out any further details or conclusions. A very quick search of the internet on the topic of the number of sexual partners seemed to indicate that for Western men and women 12 sexual partners is on the high side for most of them - actually more like half of that, after discarding "outliers". A further potential glitch in the 12-bonk rule is that it assumes when you have found your post-12-bonk lover that he or she will accept your overtures, and of course you cannot be certain of that. I am sure that someone is working on the mathematics of unrequited love. </div>
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Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com16tag:blogger.com,1999:blog-2659416969867866171.post-22461906093726905662013-02-06T21:14:00.001-08:002013-02-07T14:51:43.254-08:00100,000th Visitor<div style="text-align: justify;">
Just a short note to say that the number of visitors to this blog just passed 100,000. I had a few posts in 2007, a few more in 2008 and then picked up from there for almost 300 by now. I have been mostly absent of late (meaning the last year of so) for personal reasons but I hope to pick up again here this year. Thank you for all the visits. </div>
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<br />Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com4tag:blogger.com,1999:blog-2659416969867866171.post-39733435568812920522012-05-28T05:51:00.001-07:002012-05-28T19:14:47.187-07:00Some more Satellite Risks<div align="justify">
Back in 2009 I <a href="http://lukenotricks.blogspot.com.au/2009/06/risk-of-degradation-to-gps.html">posted</a> on the risk of GPS satellite positioning system degrading over the next few years, both in terms of coverage and accuracy, due a decrease in the number of operational satellites. This risk was the main finding of an audit performed by the Government Accountability Office (GAO), where Monte Carlo simulations predicted that the number of operational satellites would fall below the threshold required to provide positioning at agreed service levels. In short, too many satellites that were approaching, or had passed, their expected operational life were being relied on to continue functioning in the absence of replacements. Engineers know that satellites have very finite operational lifetimes, and at some point will simply stop working and start drifting. <br />
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And one significant satellite did just that last month, as <a href="http://www.economist.com/node/21554528?frsc=dg%7Cb">reported</a> by the Economist for example. The satellite in question was <a href="http://en.wikipedia.org/wiki/Envisat">Envisat</a>, one without GPS responsibilities thankfully, launched in 2002 to provide a wide range of <a href="http://en.wikipedia.org/wiki/Envisat#Mission">environmental data</a> which it has delivered handsomely in the terabyte range. It is a critical primary source of data for scientists, providing continuous observations until contact was lost last month. The European Space Agency has formally announced that the mission of Envisat has been completed, and successfully so, after celebrating it’s tenth year of operation when only five were expected – both from an engineering and funding perspective. <br />
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So Envisat was living on borrowed time, five years of it or 100% additional mission time, as the GAO report on the GPS satellite constellation was asserting. The Economist article goes on to name some culprits in the case of Envisat, with governments being allocated the lion’s share due to lack of funding. Both NASA and ESA are unwilling to sure up their Earth-observation programs without additional government guarantees. <br />
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There is another risk beyond the loss of service provided by Envisat or GPS satellites, and that is additional <a href="http://en.wikipedia.org/wiki/Space_debris">space debris</a> created by these satellites once they stop functioning. It is estimated that Envisat will orbit the Earth for the next 150 years before being drawn down into its atmosphere. During this time it will be at risk from colliding with other existing space debris, breaking into smaller pieces upon impact, producing even finer debris. This is known as the <a href="http://en.wikipedia.org/wiki/Kessler_Syndrome">Kessler Syndrome</a>, proposed by NASA scientist Donald J. Kessler in 1978, who <a href="http://www.spacesafetymagazine.com/2012/04/25/don-kessler-envisat-kessler-syndrome/">commented</a> on the Envisat demise as follows</div>
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It seems ironic that a satellite intended to monitor the Earth’s environment is at risk from the space environment and is likely to become a major contributor to the debris environment.</div>
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Orbital debris and the collisions that may result from its presence, are a significant risk for NASA. There is a 180-page <a href="http://www.nap.edu/catalog.php?record_id=13244">report</a> on this topic which, apart from the specific subject matter, contains many useful risk principles and guidelines.</div>Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com8tag:blogger.com,1999:blog-2659416969867866171.post-593841039029398522012-05-22T01:32:00.001-07:002012-05-22T01:32:37.144-07:00Chrome headed to be #1 Browser<p align="justify">Business Insider recently <a href="http://www.businessinsider.com/chart-of-the-day-top-browsers-2012-5?nr_email_referer=1&utm_source=Triggermail&utm_medium=email&utm_term=SAI%20Chart%20Of%20The%20Day&utm_campaign=SAI_COTD_052112">reported</a> that Chrome is now the number 1, or near number one browser of choice, and its popularity has come as the expense of IE as shown in the chart below </p> <p align="justify"><a href="http://lh5.ggpht.com/-vOvZ8O-IitY/T7tPG5lqgAI/AAAAAAAABOU/o26Ik5zQCV4/s1600-h/image%25255B4%25255D.png"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px; padding-top: 0px" title="image" border="0" alt="image" src="http://lh6.ggpht.com/--EC33tSw1NY/T7tPIlGIT3I/AAAAAAAABOc/aRtV4CWKJBo/image_thumb%25255B2%25255D.png?imgmax=800" width="378" height="296" /></a></p> <p align="justify">The data set is based on statistics collected by <a href="http://gs.statcounter.com/#browser-ww-weekly-201120-201220">StatCounter</a>, and is probably not reliable for specific figures but sufficiently reliable for showing trends – in this case, that Chrome is stealing market share mainly from IE and somewhat from Firefox. In any case, a significant amount of internet traffic is now being funneled through the Chrome security model. The previous browser prediction that I <a href="http://lukenotricks.blogspot.com.au/2010/05/projection-firefox-overtakes-ie-by.html">posted on</a>, that Firefox would overtake IE by Christmas 2012, agrees quite well with the data set above. </p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com1tag:blogger.com,1999:blog-2659416969867866171.post-36786252546224061532011-10-07T11:57:00.001-07:002011-10-07T11:58:30.685-07:00Crypto from Tesco<p align="justify">You can now <a href="http://www.tesco.com/tescobooks/block-cipher-companion-the/6S5-V3SZ.prd?skuId=6S5-V3SZ&pageLevel=sku&pdpSellerId=1000001&PageName=list&PageType=landing&PLPToPDPFlag=true">order</a> the new <a href="http://lukenotricks.blogspot.com/2011/06/block-cipher-bible-coming.html">Block Cipher Companion</a> book from Tesco’s, just published this month. I have seen an earlier draft and the text is very detailed and comprehensive, as you would expect from authors of this caliber. </p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com4tag:blogger.com,1999:blog-2659416969867866171.post-60016192362194624162011-10-04T08:29:00.001-07:002011-10-04T08:29:26.233-07:00Xobni becomes Smartr<p align="justify">I recently <a href="http://lukenotricks.blogspot.com/2011/10/150000-reads-of-my-scribd-documents.html">posted</a> about the reads on my Scribd collection, and one of the most frequently read is the master’s thesis by the founder of Xobni (inbox spelt backwards) called <a href="http://www.scribd.com/doc/25161724/How-to-Organize-Email">How to Organize Email</a>. There is a new version of this software called Smartr for Gmail and you can watch a <a href="http://vimeo.com/29351194">video</a> on its features. </p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com2tag:blogger.com,1999:blog-2659416969867866171.post-34110077672551084842011-10-02T15:31:00.001-07:002011-10-02T15:31:22.540-07:00Yoda Pie Chart - there is no Try<p>Love it, from <a href="http://flowingdata.com/2011/09/18/yoda-pie-chart/">Flowing Data</a>.</p> <p><a href="http://lh3.ggpht.com/-jY5LIE4SFqg/TojmMmwIfpI/AAAAAAAABJE/30O1RgyRQlo/s1600-h/image%25255B3%25255D.png"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px; padding-top: 0px" title="image" border="0" alt="image" src="http://lh6.ggpht.com/-fd6gmP5lYpo/TojmNm6bu0I/AAAAAAAABJI/-1k2SLramNo/image_thumb%25255B1%25255D.png?imgmax=800" width="361" height="278" /></a></p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com2tag:blogger.com,1999:blog-2659416969867866171.post-84172961259556432242011-10-02T09:15:00.001-07:002011-10-02T13:27:40.667-07:00150,000 reads of my Scribd documents<p align="justify">I have uploaded about 200 documents to Scribd over the last few years and the number of reads has just passed 150,000. You can see the categories <a href="http://lukenotricks.blogspot.com/p/scribd-collections.html">here</a>. The top 5 documents, each with over 3000 reads each are</p> <ul> <li><a href="http://www.scribd.com/doc/10175233/A-Data-Centric-Security-Model">A Data Centric Security Model</a> (almost 6,000 reads)</li> <li><a href="http://www.scribd.com/doc/9793125/The-Core-Components-of-the-Entrust-PKI-v5">The Core Components of the Entrust PKI v5</a> </li> <li><a href="http://www.scribd.com/doc/17065431/BA-IT-Security-Awareness-presentation">BA IT Security Awareness presentation.</a> </li> <li><a href="http://www.scribd.com/doc/25161724/How-to-Organize-Email">How to Organize Email</a> </li> <li><a href="http://www.scribd.com/doc/12723043/How-much-is-enough-A-Risk-Management-Approach-to-Computer-Security">How much is enough? A Risk Management Approach to Computer Security</a> </li> </ul> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com2tag:blogger.com,1999:blog-2659416969867866171.post-15874827505999327942011-09-29T16:12:00.001-07:002011-09-29T16:12:03.219-07:00The Other Binomial Expansion<p>From this <a href="http://www.scribd.com/doc/13649407/Funny-Exam-Answers">collection</a> of creative exam answers. </p> <p><a href="http://lh6.ggpht.com/-yYHVHzOjHc8/ToT7PlGngVI/AAAAAAAABI8/pHZVB6UTfIw/s1600-h/image%25255B4%25255D.png"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px; padding-top: 0px" title="image" border="0" alt="image" src="http://lh6.ggpht.com/-8lnsgTZsDhs/ToT7QuznijI/AAAAAAAABJA/Vw2M0bIa3pc/image_thumb%25255B2%25255D.png?imgmax=800" width="335" height="317" /></a></p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com2tag:blogger.com,1999:blog-2659416969867866171.post-9935936177081344272011-09-26T15:47:00.001-07:002011-09-26T15:47:11.664-07:00SHA post as SPAM magnet<p align="justify">Don’t ask me why but a lot of SPAM has accrued, and keeps accruing, at this <a href="http://lukenotricks.blogspot.com/2009/05/cost-of-sha-1-collisions-reduced-to-252.html">May 2009 post on SHA-1</a>. Apart from the common penis enlargement references, some of the other SPAM is quite long and seems to be playing on some quirk of SEO. Fine. </p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com2tag:blogger.com,1999:blog-2659416969867866171.post-57727104248333951522011-09-25T08:49:00.001-07:002011-09-25T08:49:58.058-07:00Fibonacci Pigeons<p>This just made me laugh.</p> <p><a href="http://lh4.ggpht.com/-aVIgpY9G6j0/Tn9No8a5leI/AAAAAAAABI0/U7OUd1S7Czo/s1600-h/image%252520%2525287275%252529%25255B4%25255D.jpg"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px; padding-top: 0px" title="image (7275)" border="0" alt="image (7275)" src="http://lh4.ggpht.com/-AoW2u4Rd2Lw/Tn9NpVrjBFI/AAAAAAAABI4/gGiXDwWs23w/image%252520%2525287275%252529_thumb%25255B2%25255D.jpg?imgmax=800" width="377" height="235" /></a></p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com57tag:blogger.com,1999:blog-2659416969867866171.post-74975212017417651202011-09-22T08:15:00.001-07:002011-10-02T15:31:55.464-07:00These aren’t the key management systems you are looking for<p align="justify"><a href="http://storageconference.org/2010/Presentations/KMS/9.Stieber.pdf">This</a> is a nice presentation on enterprise key management issues from Anthony Stieber given at the <a href="http://storageconference.org/2010/Presentations/KMS/Videos-HD.html#2">2nd IEEE (KMS 2010) Key Management Summit</a><font size="2"><font style="font-weight: normal">. The main message is that KMS is tricky and don’t roll your own. By the way if you are looking for examples of Powerpoint that breaks all the rules for good presentations, then you will find them here. </font></font></p> <p></a></p> <p><a href="http://lh4.ggpht.com/-t6-mBC9H8Wk/TntRHjiWiWI/AAAAAAAABIk/dIx8eRu2BZg/s1600-h/image%25255B10%25255D.png"><img style="background-image: none; border-right-width: 0px; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top-width: 0px; border-bottom-width: 0px; margin-left: auto; border-left-width: 0px; margin-right: auto; padding-top: 0px" title="image" border="0" alt="image" src="http://lh6.ggpht.com/-4LGt2y-OV5I/TntRIbwBCSI/AAAAAAAABIo/fnfdebHfck8/image_thumb%25255B6%25255D.png?imgmax=800" width="360" height="275" /></a></p> <p align="justify">Also there is a very polished and informative <a href="http://storageconference.org/2010/Presentations/KMS/12.Kostick.pdf">presentation</a> from Chris Kostick of E & Y on an enterprise key management maturity model, and below is a comprehensive diagram on the life-cycle management of keys. </p> <p align="justify"><a href="http://lh4.ggpht.com/-RCv5UpxzXAI/TntUydKzEJI/AAAAAAAABIs/KPcs6WV8IFQ/s1600-h/image%25255B11%25255D.png"><img style="background-image: none; border-right-width: 0px; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top-width: 0px; border-bottom-width: 0px; margin-left: auto; border-left-width: 0px; margin-right: auto; padding-top: 0px" title="image" border="0" alt="image" src="http://lh3.ggpht.com/-s9VCiD0eRxE/TntUy_8w2hI/AAAAAAAABIw/-dCMrc-LjV0/image_thumb%25255B7%25255D.png?imgmax=800" width="383" height="259" /></a></p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com2tag:blogger.com,1999:blog-2659416969867866171.post-59181533979827708032011-09-22T07:10:00.001-07:002011-09-22T07:10:16.224-07:00Liability for Risk Decisions<p align="justify"><a href="http://lh6.ggpht.com/-jZDC5X4zyGw/TntBxHYG3II/AAAAAAAABIU/8lrRiNRQplM/s1600-h/image%25255B3%25255D.png"><img style="background-image: none; border-bottom: 0px; border-left: 0px; margin: 0px 6px 0px 0px; padding-left: 0px; padding-right: 0px; display: inline; float: left; border-top: 0px; border-right: 0px; padding-top: 0px" title="image" border="0" alt="image" align="left" src="http://lh6.ggpht.com/-G9Qa0uFLj18/TntBx7UvHQI/AAAAAAAABIY/SkoJ3JkBm2A/image_thumb%25255B1%25255D.png?imgmax=800" width="121" height="182" /></a>I am currently in-between positions, somewhat happily, and are casting my net of interest a bit wider than my traditional roles in IT Security and Risk. One position that caught my eye from a global reinsurer in town was the role of <a href="http://www.scribd.com/doc/65899032/Job-description-for-an-Earthquake-Analyst">Earthquake Expert</a> within their Natural Catastrophe department (or Nat Cat in insurance lingo). I really don’t have any specific background in this area but I sometimes entertain the idea that I can transfer hard-learnt crypto math skills into a numerate role like this one which calls for extensive modeling and prediction. You also think that this might be a nice and cozy niche area to ply your trade as a specialist, holding something of a privileged position. </p> <p align="justify">Well I was disabused of any such notion this week when I <a href="http://www.bbc.co.uk/news/world-europe-14981921">read</a> this week of six Italian scientists and a former government official are being put on trial for the alleged manslaughter of the 309 people who died in the 2009 L'Aquila earthquake in Italy.</p> <p align="justify">The seven defendants were members of a government panel, called the Serious Risks Commission (seriously), who were asked to give an opinion (or risk statement) on the likelihood that  L'Aquila would be struck by a major earthquake, based on an analysis of the smaller tremors that the city was experiencing over the previous few months. The panel verdict delivered in March stated that there was "no reason to believe that a series of low-level tremors was a precursor to a larger event". A week later the city suffered an earthquake of magnitude 6.3 on the <a href="http://en.wikipedia.org/wiki/Richter_magnitude_scale#Richter_magnitudes">Richter Scale</a>, denoting a “strong quake”.</p> <p align="justify">The crux of the case against the scientists is that they did not predict the strong quake coming to L'Aquila to allow a proper evacuation of its inhabitants. The defense rebuttal is simply that such a prediction is impossible, and they cannot be held accountable for this unreasonable expectation. The scientists cannot be expected to function as a reliable advanced warning system. The international scientific community has weighed in to support the defendants with <a href="http://www.aaas.org/news/releases/2010/media/0630italy_letter.pdf">a one-page letter</a> from the American Association for the Advancement of Science, which supported the scientists by saying that there is no reliable scientific process for earthquake prediction, and they should not be treated as criminals for adhering to the accepted practices of their field.</p> <p align="justify">Recently people were evacuated from New York City as precaution to the impact of <a href="http://en.wikipedia.org/wiki/Hurricane_Irene_%282011%29">Hurricane Irene</a>. The hurricane passed by New York causing far less extensive damage than expected, and yet there were still complaints from residents about being asked to leave their homes “unnecessarily”. It seems that authorities cannot win in these matters unless they can predict the future accurately. </p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com0tag:blogger.com,1999:blog-2659416969867866171.post-13822074852099222402011-09-14T18:38:00.001-07:002011-09-17T01:51:27.266-07:00PageRank Increment for No Tricks<p align="justify"><a href="http://lh4.ggpht.com/-dERIhcXOIEU/TnFXGgjgHGI/AAAAAAAABHo/iubjIsbdV6w/s1600-h/image%25255B7%25255D.png"><img style="background-image: none; border-right-width: 0px; margin: 0px 9px 0px 0px; padding-left: 0px; padding-right: 0px; display: inline; float: left; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px; padding-top: 0px" title="image" border="0" alt="image" align="left" src="http://lh5.ggpht.com/-BvBHNAox77A/TnFXHFmfBHI/AAAAAAAABHs/pFgQ7dofSoQ/image_thumb%25255B2%25255D.png?imgmax=800" width="108" height="111" /></a></p> <p align="justify">Every now and again I run this blog through the free <a href="http://websitegrader.com/">Website Grader</a> tool which measures your site on a variety of criteria, hoping to lure you for a more thorough paid analysis. The tool used to report a PageRank value, and No Tricks seemed to be stuck at 3 for quite a few years. The site now uses there own page ranking metric, which reported a value higher than 3. I was overjoyed and eagerly confirmed that the “true” PageRank metric had also increased from 3 to 4, representing some form of “exponential” improvement since the scale is logarithmic. I can now claim that the No Tricks site has gone from being of “low importance” to being of “medium importance”. Fine, I’ll take it. </p> <p align="justify">Incidentally, I <a href="http://lukenotricks.blogspot.com/2008/10/wisdom-of-random-crowd-of-one.html">wrote</a> a short introduction to the mathematics of PageRank a few years back, with a security spin. </p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com55tag:blogger.com,1999:blog-2659416969867866171.post-53634246152062751722011-09-14T07:10:00.001-07:002011-09-14T15:56:52.703-07:00Jesus and spending a trillion dollars<p align="justify"><a href="https://profiles.google.com/amit.labnol">Amit Agarwal</a> at Digital Inspiration has put together some <a href="http://www.labnol.org/internet/visualize-numbers-how-big-is-trillion-dollars/7814/">information</a> on just how big the number one trillion actually is, in human-sized terms. We have heard a lot about trillions of dollars in the context of credit crisis and, more recently, in the debate over the US budget deficit. Not to mention that Facebook recently <a href="http://lukenotricks.blogspot.com/2011/09/all-eyes-on-facebook.html">reported</a> that their total number of page views has passed the one trillion mark. </p> <p align="justify">Agarwal started by reporting the following Biblical metaphor</p> <blockquote> <p align="justify">If you start spending a million dollars every single day since <a href="http://www.biblequestions.org/Archives/BQAR373.htm">Jesus was born</a>, you still wouldn't have spent a trillion dollars by today.</p> </blockquote> <p align="justify">And in terms of a diagram, Agarwal starts with takes a single 100 dollar US bill, and represents larger values as</p> <p align="justify"><a href="http://lh5.ggpht.com/-dK9f2qRy0pM/TnC12ZcbUtI/AAAAAAAABHE/u5znn7t-ZdM/s1600-h/image%25255B6%25255D.png"><img style="background-image: none; border-right-width: 0px; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top-width: 0px; border-bottom-width: 0px; margin-left: auto; border-left-width: 0px; margin-right: auto; padding-top: 0px" title="image" border="0" alt="image" src="http://lh5.ggpht.com/-wlDseL1exs0/TnC12vBSBjI/AAAAAAAABHI/Xt2OvHXV7dY/image_thumb%25255B2%25255D.png?imgmax=800" width="240" height="226" /></a></p> <p align="justify">Extending further, a trillion dollars then requires a football field of space, as shown below, with our human-sized man dwarfed in the bottom left corner. </p> <p align="justify"><a href="http://lh3.ggpht.com/-Z0GsfsHUC_g/TnC13VupnmI/AAAAAAAABHM/cTTj63xtZfY/s1600-h/image%25255B7%25255D.png"><img style="background-image: none; border-right-width: 0px; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top-width: 0px; border-bottom-width: 0px; margin-left: auto; border-left-width: 0px; margin-right: auto; padding-top: 0px" title="image" border="0" alt="image" src="http://lh5.ggpht.com/-XPDzkJshQG0/TnC13h0WvXI/AAAAAAAABHQ/6Vd5fRb3LPc/image_thumb%25255B3%25255D.png?imgmax=800" width="240" height="110" /></a></p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com26tag:blogger.com,1999:blog-2659416969867866171.post-78317371851362217672011-09-14T02:20:00.001-07:002011-09-19T15:16:37.740-07:00Can you win the lottery too many times?<p align="justify">Last year I posted on <a href="http://lukenotricks.blogspot.com/2010/03/fabled-25-sigma-event.html">The Fabled 25 Sigma Event</a>, referring to a quote from <a href="http://en.wikipedia.org/wiki/David%20Viniar">David Viniar</a>, then CFO of <a href="http://www.gs.com/">Goldman Sachs</a>, who was attempting to describe the magnitude of the movements in the financial markets. Mr. Viniar probably did not fully understand the implications of what he was saying, since a 25 sigma event translates into a phenomenon occurring once every 10^{135} years - a period of time that we have yet to see even a fraction of. Several researchers at the business school of the <a href="http://maps.google.com/maps?ll=53.3083333333,-6.22222222222&spn=0.01,0.01&q=53.3083333333,-6.22222222222%20%28University%20College%20Dublin%29&t=h">University College Dublin</a> gave another interpretation of how unlikely this event was by stating that it equates to winning the UK lottery more than 20 times in a row. </p> <p align="justify">Winning the lottery 20 times does seem very unlikely. Recently a woman won the Texas lottery for the fourth time in the last 10 years or so, accumulating prize money of  just over 20 million USD, and is being scrutinized by the press for potential fraud. There is a lot of suspicion about the luck of Joan Ginther (pictured below) and her winning streak. Googling on “4 time lottery winner” produces pages of articles on Ginther’s supposed luck. </p> <p align="justify"><a href="http://lh5.ggpht.com/-1jWnEyfQszk/TnCPdHb8K4I/AAAAAAAABGs/Tjvcvccmssg/s1600-h/image%25255B3%25255D.png"><img style="background-image: none; border-right-width: 0px; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top-width: 0px; border-bottom-width: 0px; margin-left: auto; border-left-width: 0px; margin-right: auto; padding-top: 0px" title="image" border="0" alt="image" src="http://lh6.ggpht.com/-icNvNZraTEw/TnCPeAXd0CI/AAAAAAAABGw/8TlxNf4_a3g/image_thumb%25255B1%25255D.png?imgmax=800" width="244" height="182" /></a></p> <p align="justify">Nathaniel Rich ran an interesting <a href="http://www.scribd.com/doc/60495831/Nathaniel-Rich-The-Luckiest-Woman-on-Earth-Three-Ways-to-Win-the-Lottery">4-page story</a> in the August issue of Harper’s magazine, where he visits the small Texas town of Bishop to look at the lone town store where three of the winning tickets were purchased. Rich spoke to enough mathematics professors beforehand to determine that the odds of an individual winning four times by pure luck are extremely low indeed, about 10^{-24}, or a practical impossibility (still “far more likely” than a 25 sigma event though). The alternate scenarios are (1) an inside job potentially amongst the state lotteries and their suppliers (2) cracking the parameters of the psuedo-random number generator for selecting the winners, and (3) dumb luck, or increasing your odds of winning by buying many tickets. The most likely answer seems to be a combination of (2) and (3). </p> <p align="justify">The local town people are going with scenario 3 or just ascribing it to pure luck outright, as there is a strong (American) belief that everyone can be a winner. Getting back to those 25 sigma events, it seems then that no one would actually be able to win the UK lottery over 20 times as they would be suspected of foul play, and likely to find themselves arrested way before that many wins. Perhaps Mr. Viniar should have been arrested for his remarks.</p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com317tag:blogger.com,1999:blog-2659416969867866171.post-7695493286240372322011-09-13T04:48:00.001-07:002011-09-14T14:49:43.670-07:00An unexpected business model for Angry Birds<p align="justify">Rovio, the company that developed Angry Birds, recently <a href="http://www.businessinsider.com/rovio-is-selling-1-million-angry-birds-t-shirts-and-plush-toys-every-month-2011-9">announced</a> at the Techcrunch Disrupt conference that they are now selling more than one million Angry Birds T-shirts and toys each month. That’s after 350 million downloads of the game. What a business model, if they were intending it, and a movie deal is apparently in the works as well. Oh yes, and a theme park. So it seems it is possible to use a mobile game as the basis to leverage the creation of real world profits. </p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com2tag:blogger.com,1999:blog-2659416969867866171.post-91297947626526097412011-09-13T01:09:00.001-07:002011-09-13T01:24:34.242-07:00All Eyes on Facebook<p align="justify">A recent social media <a href="http://blog.nielsen.com/nielsenwire/social/">report</a> from Nielsen’s shows, amongst other things, that Facebook dominates our attention on the Internet, larger in terms of minutes of face time than the four next most popular social media sites. Business Insider produced the following <a href="http://www.businessinsider.com/chart-of-the-day-facebook-time-2011-9">chart</a> based on Nielsen’s data</p> <p><a href="http://lh5.ggpht.com/-sSj1QEi2P20/Tm8PoElBVOI/AAAAAAAABGc/-p9wmfc76MU/s1600-h/image%25255B3%25255D.png"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px; padding-top: 0px" title="image" border="0" alt="image" src="http://lh4.ggpht.com/-f9bVzNSsaK8/Tm8Polf2KWI/AAAAAAAABGg/D7ce-eVtu_s/image_thumb%25255B1%25255D.png?imgmax=800" width="343" height="264" /></a></p> <p align="justify">It was <a href="http://venturebeat.com/2011/08/24/facebook-trillion-pageviews/">recently</a> (and widely) reported that the number of page views on Facebook passed the 1 trillion mark, but that figure has been <a href="http://www.pcmag.com/article2/0,2817,2391959,00.asp">disputed</a>. In any case, all internet path seems to lead to Facebook one way or the other. </p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com0tag:blogger.com,1999:blog-2659416969867866171.post-20039986091726818982011-09-11T04:47:00.001-07:002011-09-11T04:47:06.948-07:00A short touching remark on 9/11<p align="justify">I am stepping out more of late, meeting new people and doing new things, which has seen more doing far less blogging over the last year. One of the site I use to find things to do is <a href="http://www.meetup.com/">Meetup</a> in the Zurich locality. I received the following email from the founder today who relates how the origin of the service was 9/11, and his intention was to “use the internet to get people off the internet”,</p> <p>Fellow Meetuppers, <br />I don't write to our whole community often, but this week is <br />special because it's the 10th anniversary of 9/11 and many <br />people don't know that Meetup is a 9/11 baby. <br />Let me tell you the Meetup story. I was living a couple miles <br />from the Twin Towers, and I was the kind of person who thought <br />local community doesn't matter much if we've got the internet <br />and tv. The only time I thought about my neighbors was when I <br />hoped they wouldn't bother me.</p> <p> <br />When the towers fell, I found myself talking to more neighbors <br />in the days after 9/11 than ever before. People said hello to <br />neighbors (next-door and across the city) who they'd normally <br />ignore. People were looking after each other, helping each <br />other, and meeting up with each other. You know, being <br />neighborly.</p> <p> <br />A lot of people were thinking that maybe 9/11 could bring <br />people together in a lasting way. So the idea for Meetup was <br />born: Could we use the internet to get off the internet -- and <br />grow local communities?</p> <p> <br />We didn't know if it would work. Most people thought it was a <br />crazy idea -- especially because terrorism is designed to make <br />people distrust one another. <br />A small team came together, and we launched Meetup 9 months <br />after 9/11.</p> <p> <br />Today, almost 10 years and 10 million Meetuppers later, it's <br />working. Every day, thousands of Meetups happen. Moms Meetups, <br />Small Business Meetups, Fitness Meetups... a wild variety of <br />100,000 Meetup Groups with not much in common -- except one <br />thing.</p> <p> <br />Every Meetup starts with people simply saying hello to <br />neighbors. And what often happens next is still amazing to me. <br />They grow businesses and bands together, they teach and <br />motivate each other, they babysit each other's kids and find <br />other ways to work together. They have fun and find solace <br />together. They make friends and form powerful community. It's <br />powerful stuff.</p> <p> <br />It's a wonderful revolution in local community, and it's thanks <br />to everyone who shows up. <br />Meetups aren't about 9/11, but they may not be happening if it <br />weren't for 9/11.</p> <p> <br />9/11 didn't make us too scared to go outside or talk to <br />strangers. 9/11 didn't rip us apart. No, we're building new <br />community together!!!!</p> <p> <br />The towers fell, but we rise up. And we're just getting started <br />with these Meetups.</p> <p> <br />Scott Heiferman (on behalf of 80 people at Meetup HQ) <br />Co-Founder & CEO, Meetup <br />New York City <br />September 2011</p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com2tag:blogger.com,1999:blog-2659416969867866171.post-85412297652172888422011-09-10T13:30:00.001-07:002011-09-19T15:14:03.836-07:00The “Half-life” of a bitly link is about 3 hours<p align="justify"><a href="http://www.hilarymason.com/">Hilary Mason</a>, Chief Scientist at <a href="http://bit.ly">bit.ly</a>, a large link shortening service, has done an analysis on some of their link data to get an idea of how long links remain “alive” or “popular”. The measure was to look at 1,000 links and graph the number of hits that a link receives over 80,000 seconds (almost a day), and then determine the point over that period where half of the total number of hits were received. From the <a href="http://blog.bitly.com/post/9887686919/you-just-shared-a-link-how-long-will-people-pay">post</a></p> <blockquote> <p align="justify">So we looked at the half life of 1,000 popular <a href="http://bit.ly/">bitly</a> links and the results were surprisingly similar. The mean half life of a link on twitter is 2.8 hours, on facebook it’s 3.2 hours and via ‘direct’ sources (like email or IM clients) it’s 3.4 hours. So you can expect, on average, an extra 24 minutes of attention if you post on facebook than if you post on twitter.</p> </blockquote> <p align="justify">Running the data yielded the following graph, showing a strong power law for Facebook, Twitter and direct links (links shared via email, and instant messengers), but a delayed curve for YouTube.</p> <p align="justify"><a href="http://lh3.ggpht.com/-toBevkv6AyQ/TmvI-kaVagI/AAAAAAAABGM/gcxtXPTznM4/s1600-h/image%25255B3%25255D.png"><img style="background-image: none; border-right-width: 0px; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top-width: 0px; border-bottom-width: 0px; margin-left: auto; border-left-width: 0px; margin-right: auto; padding-top: 0px" title="image" border="0" alt="image" src="http://lh5.ggpht.com/--FPauS4ayxM/TmvI_F_hKAI/AAAAAAAABGQ/WCjCJ4YELFM/image_thumb%25255B1%25255D.png?imgmax=800" width="396" height="234" /></a></p> <p align="justify">What Mason computed would more accurately be called the <a href="http://en.wikipedia.org/wiki/Median">median</a> rather than the <a href="http://en.wikipedia.org/wiki/Half_life">half-life</a>, since she is interested in the first point in time that divides the total number of hits for the period into two roughly equal sets. More discussion on this point is given in the comments to the post. The conclusion from the post</p> <blockquote> <p align="justify">In general, <strong>the half life of a bitly link is about 3 hours</strong>, unless you publish your links on youtube, where you can expect about 7 hours worth of attention. Many links last a lot less than 2 hours; other more sticky links last longer than 11 hours over all the referrers. This leads us to believe that the lifespan of your link is connected more to what content it points to than on where you post it: on the social web it’s all about what you share, not where you share it!</p> </blockquote> <p align="justify">A while back I <a href="http://lukenotricks.blogspot.com/2009/05/half-life-of-vulnerabilities-is-still.html">posted</a> on the half-life of patching vulnerabilities being 30 days and there we probably have confusion with the sample median as well. I also noted the attrition for my own links in <a href="http://lukenotricks.blogspot.com/2010/05/shark-fin-posts.html">Shark Fin posts</a>. </p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com1tag:blogger.com,1999:blog-2659416969867866171.post-5953626228501611182011-09-09T10:10:00.001-07:002011-09-11T02:41:32.388-07:00Two victories for Randomness<p align="justify">I recently came across two smallish examples of where randomness was the solution to two perplexing problems. That is, rolling the dice seems to help you out of a situation where a planned method was not giving you what you wanted. </p> <p align="justify">The first issue is the problem of how to board passengers on a plane. Finding the best way to board people is actually a well-studied problem, both theoretically and in practice, and you can see some of the work <a href="http://leeds-faculty.colorado.edu/vandenbr/projects/boarding/boarding.htm#section4">here</a>. At the <a href="http://leeds-faculty.colorado.edu/vandenbr/projects/boarding/boarding.htm#section1">top</a> of the same page there is a nice simulation program which shows you how different boarding strategies play out, and random boarding (just calling out people to board at random) is better than the usual front-to-back boarding that most of us are familiar with. </p> <p align="justify"><a href="http://lh6.ggpht.com/-axbzytovK0Y/TmpIim8FC_I/AAAAAAAABGE/8qcoALpha-U/s1600-h/image%25255B3%25255D.png"><img style="background-image: none; border-right-width: 0px; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top-width: 0px; border-bottom-width: 0px; margin-left: auto; border-left-width: 0px; margin-right: auto; padding-top: 0px" title="image" border="0" alt="image" src="http://lh5.ggpht.com/--24kxjCpxJI/TmpIjqJIc7I/AAAAAAAABGI/R0nE4n_8sQM/image_thumb%25255B1%25255D.png?imgmax=800" width="209" height="157" /></a></p> <p align="justify">The reason is that random boarding gives a better utilization of the space in the plane whereas front-to-back boarding piles people into one part of the plane, eventually causing jams in the aisles. The full set of strategies examined are</p> <ul> <li>Back-to-front </li> <li>Rotating-zone </li> <li>Random </li> <li>Block </li> <li>Outisde-in </li> <li>Reverse-pyramid </li> </ul> <p align="justify">On another topic, a Freakonomics blog <a href="http://www.freakonomics.com/2011/08/10/how-rolling-dice-helps-save-leopards/">post</a> describes how researchers in South Africa are using a randomness trick to get truthful answers from farmers who are suspected of illegally killing leopards and hyenas. The method is called <a href="http://en.wikipedia.org/wiki/Randomized_response">randomized response</a> surveying, where when the farmers are asked potentially incriminating questions they first flip a coin, and based on the result give a yes or no answer to either the incriminating question if it was heads, or a harmless question (do you think the Springboks will win the RWC?) if it was tails. The farmers actually used a die, taking specific actions on which value from 1 to 6 was thrown, but the principle is the same as I have described it. </p> <p align="justify">The trick here is that the person asking the question cannot tell which question the farmer is answering, but the farmer’s answer can be recorded. Statistical methods can then be used to determine the distribution of answers for the two questions, and actually make inferences about the proportion of positive answers to the incriminating question. This method was devised in the 60’s, and by the early 80’s it was being taught at my undergraduate university as part of a first year course. </p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com1tag:blogger.com,1999:blog-2659416969867866171.post-40531506325224975742011-08-07T14:36:00.001-07:002011-08-07T16:08:01.900-07:00Green IT Swiss Data Center presentation<p align="justify"><a href="http://www.green.ch/LinkClick.aspx?fileticket=jAU9RTXh16A%3d&tabid=224&mid=1713">Here</a> is a short presentation on a relatively new data center in the west of Zurich that is designed to be green and secure.  More information at <a href="http://www.green.ch/deCH/Privatkunden.aspx">green.ch</a>, and the language can be changed to English in the upper right corner. </p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com2tag:blogger.com,1999:blog-2659416969867866171.post-38352068376709928652011-08-07T13:11:00.001-07:002011-08-07T13:11:05.984-07:00US Grade Inflation Study<p align="justify">A recent <a href="http://www.gradeinflation.com/tcr2010grading.pdf">study</a> has examined the prevalence of grade inflation at US universities over the last 100 years or so, and has found some identifiable patterns. The chart below shows the increase in grades between various types of schools in the primary colors, with the grey representing (unnamed individual schools).</p> <p><a href="http://lh3.ggpht.com/-zGL_MCDc02A/Tj7xUyiJCHI/AAAAAAAABFk/Toj2DVUPiNU/s1600-h/image%25255B3%25255D.png"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="image" border="0" alt="image" src="http://lh5.ggpht.com/-rG5HkfDeh58/Tj7xWVldGVI/AAAAAAAABFo/BCgSjx3OT9Q/image_thumb%25255B1%25255D.png?imgmax=800" width="382" height="234" /></a></p> <p align="justify">What is clear is that there was a huge increase in grade in crease in the 60’s and then a steady increase over  the last 30 years of so. From the study</p> <blockquote> <p align="justify">The rise in grades in the 1960s correlates with the social upheavals of the Vietnam War. It was followed by a decade <br />period of static to falling grades. The cause of the renewal of grade inflation, which began in the 1980s and has yet to <br />end, is subject to debate, but it is difficult to ascribe this rise in grades to increases in student achievement. Students’ entrance test scores have not increased (College Board, 2007), students are increasingly disengaged from their studies (Saenz et al., 2007), and the literacy of graduates has declined (Kutner et al., 2006). A likely influence is the emergence of the now common practice of requiring student-based evaluations of college teachers. Whatever the cause, colleges and universities are on average grading easier than ever before.</p> </blockquote> <p align="justify">Further science and engineering students are graded more harshly than their fellow students in liberal arts degrees. </p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com1tag:blogger.com,1999:blog-2659416969867866171.post-39063291727804778282011-08-07T12:49:00.001-07:002011-08-07T12:51:31.397-07:00A 10% Tipping Point Threshold<p align="justify">Scientists at Rensselaer Polytechnic Institute have recently <a href="http://pre.aps.org/abstract/PRE/v84/i1/e011130">published</a> research into social networks which indicates  that when just 10 percent of a network steadfastly holds a given belief, then that belief will eventually be adopted by the majority of the society. These group of 10% “believers” are referred to as a committed minority. </p> <p align="justify">Even though the research has produced quite a bit of press (see <a href="http://www.sciencedaily.com/releases/2011/07/110725190044.htm">here</a> and <a href="http://www.sciencedaily.com/releases/2011/07/110725190044.htm">here</a> for example) it is a little difficult to say how the result was arrived at. The abstract of the paper states that</p> <blockquote> <p align="justify">We show how the prevailing majority opinion in a population can be rapidly reversed by a small fraction p of randomly distributed committed agents who consistently proselytize the opposing opinion and are immune to influence. Specifically, we show that when the committed fraction grows beyond a critical value p<sub>c</sub>≈10%, there is a dramatic decrease in the time T<sub>c</sub> taken for the entire population to adopt the committed opinion. In particular, for complete graphs we show that when p<p<sub>c</sub>, T<sub>c</sub>~exp[α(p)N], whereas for p>p<sub>c</sub>, T<sub>c</sub>~lnN. We conclude with simulation results for Erdős-Rényi random graphs and scale-free networks which show qualitatively similar behavior.</p> </blockquote> <p align="justify">It seems that they are using a model for the spread of opinion overlayed on various network topologies, starting with the complete graph (everyone knows everyone), then scale free, and a simulation of a <a href="http://en.wikipedia.org/wiki/Random_graphs">random graph</a> process. The results are strengthened by finding the 10% threshold present in each topology. Even so, the following graph was not that informative for me.</p> <p align="justify"><a href="http://lh3.ggpht.com/-unI-KNAOLek/Tj7sRxwdvQI/AAAAAAAABFc/HWI6MvxbgWE/s1600-h/image%25255B4%25255D.png"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="image" border="0" alt="image" src="http://lh4.ggpht.com/-DE8d8NIGwhk/Tj7sSh17faI/AAAAAAAABFg/0-22er7IWPY/image_thumb%25255B2%25255D.png?imgmax=800" width="389" height="268" /></a></p> <p>I think I will have to wait get a copy of the paper to make full sense of the result. Reported in <a href="http://www.freakonomics.com/2011/07/28/minority-rules-why-10-percent-is-all-you-need/">Freakanomics</a>.</p> Anonymoushttp://www.blogger.com/profile/16153635896554944056noreply@blogger.com5