Jekyll2018-10-15T11:16:34+02:00/feed.xmlStandard DigressionWhere digression is a virtue
Joss NoirelUnexpected connections2018-10-03T00:00:00+02:002018-10-04T00:04:13+02:00/2018/10/03/unexpected_connections<p>Today, it occurred to me</p>
<ul>
<li>exponential distribution</li>
<li>birthday paradox</li>
</ul>
<p>-birthday paradox - Jukes-Cantor</p>Joss NoirelToday, it occurred to meBirthday paradox in the class room2018-09-28T00:00:00+02:002018-09-28T11:47:33+02:00/2018/09/28/birthday_paradox_in_the_classroom<h1 id="birthday-paradox-in-the-class-room">Birthday paradox in the class room</h1>
<p>In my experience, the <a href="https://en.wikipedia.org/wiki/Birthday_paradox">birthday paradox</a> — or “birthday problem” — is a great introduction to probabilities. It generally is an effective way to convey the idea that our intuition can be misguided in its evaluation of the odds of something happening. The theory of probability will then appear as a reasonable crutch for our failing intuition… Provided we can come up with a reasonable model, of course.</p>
<p>Anyway, to get people hooked on the problem, I like to carry out the experiment with the class themselves. Unfortunately, the number of students I have is generally less than the coveted 23. But that doesn’t mean that it’s not worth a try… I’m generally quite risk-averse, but that kind of risk I can handle.</p>
<p>First, even if there are only 20 students, the chances of success (identical birthdays) remain relatively high 41%. That’s <em>a lot</em> better than most gambling games. (And think how valuable the reward is in terms of interactions in the class room!)</p>
<p>Second, there’s a good chance that two students will have an identical birthday or at least adjacent birthdays (like 3 May and 4 May). This is generally seen as remarkable enough and will work.</p>
<p>But how about 15 students? or 12 students?</p>
<p>This leads to a “weak birthday problem”, which consists in looking what is the maximum distance between the closest birthdays in a group of (n) people.</p>
<p><img src="2018-09-28-birthday_paradox_in_the_classroom_files/figure-gfm/unnamed-chunk-2-1.png" /><!-- --></p>
<p>Interestingly, you have more than a 50% chance of finding two people with birthdays one day apart in a room of twelve people (8 Dec and 10 Dec), a lot less than the expected one-month difference.</p>Joss NoirelBirthday paradox in the class roomJournal Club2018-09-26T00:00:00+02:002018-09-28T11:14:36+02:00/2018/09/26/jc<p>Cédric Coulonges on 26 September talked about two papers.</p>
<ul>
<li>Zeng P, Zhou X. 2017. Non-parametric genetic prediction of complex traits with latent Dirichlet process regression models. <em>Nat Commun</em> 8 (1), 456 (<a href="https://www.nature.com/articles/s41467-017-00470-2">full text</a>)</li>
</ul>
<p>What is the genetic architecture of the complex traits. Different models make different assumptions about the distribution of effect sizes. This paper describes a method that automatically chooses the best underlying distribution based on the genetic data; this makes for greater statistical power.</p>
<ul>
<li>Khera AV et al. 2018. Genome-wide polygenic scores for common diseases identify individuals with risk equivalent to monogenic mutations. <em>Nat Genet</em> 50 (9), 1219–1224 (PMID: <a href="https://www.ncbi.nlm.nih.gov/pubmed/30104762">30104762</a>)</li>
</ul>
<p>The second paper was an important read. The polygenic score has become a promising approach with applications ranging from bioengineering to precision medicine. Although its use in the clinic is yet a little far, a letter in Nature Genetics shows its potentiel in identifying high-risk patients.</p>
<p>This also highlighted the potential use of LDPred in our own analyses.</p>Joss NoirelCédric Coulonges on 26 September talked about two papers.Le Forum de l’inscription 2017 c’est fini2017-09-17T00:00:00+02:002017-09-17T14:28:34+02:00/cnam/2017/09/17/forum_de_l_inscription<p>Le Forum de l’inscription, durant lequel le CNAM accueille ses futurs auditeurs, est fini. Ambiance un peu spéciale cette année puisque cela avait lieu dans la “Salle des textiles”.</p>Joss NoirelLe Forum de l’inscription, durant lequel le CNAM accueille ses futurs auditeurs, est fini. Ambiance un peu spéciale cette année puisque cela avait lieu dans la “Salle des textiles”.