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10 AM Tue 13-Feb Genomics, Computing, Economics Harvard Biophysics 101 (MIT-OCW Health Sciences & Technology 508)MIT-OCW Health Sciences & Technology 508 http://openwetware.org/wiki/Harvard:Biophysics_101/2007
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Binomial, Poisson, Normal
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p and q p q q = 1 – p two types of object or event. Factorials 0! = 1 n! = n(n-1)! Combinatorics (C= # subsets of size X are possible from a set of total size of n) n! X!(n-X)! C(n,X) B(X) = C(n, X) p X q n-X np 2 npq (p+q) n = B(X) = 1 Binomial frequency distribution as a function of X {int n} B(X: 350, n: 700, p: 0.1) = 1.53148×10 -157 = PDF[ BinomialDistribution[700, 0.1], 350] Mathematica ~= 0.00 = BINOMDIST(350,700,0.1,0) Excel
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P(X) = P(X-1) X = x e - X! 2 n large & p small P(X) B(X) np For example, estimating the expected number of positives in a given sized library of cDNAs, genomic clones, combinatorial chemistry, etc. X= # of hits. Zero hit term = e - Poisson frequency distribution as a function of X {int }
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Z= (X- Normalized (standardized) variables N(X) = exp(- 2 /2) / (2 ) 1/2 probability density function npq large N(X) B(X) Normal frequency distribution as a function of X {- }
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Expectation E (rth moment) of random variables X for any distribution f(X) First moment= Mean variance 2 and standard deviation E(X r ) = X r f(X) E(X) 2 E[(X- 2 ] Pearson correlation coefficient C= cov(X,Y) = X- X ) Y- Y )]/( X Y ) Independent X,Y implies C but C 0 does not imply independent X,Y. (e.g. Y=X 2 ) P = TDIST(C*sqrt((N-2)/(1-C 2 )) with dof= N-2 and two tails. where N is the sample size. Mean, variance, & linear correlation coefficient www.stat.unipg.it/IASC/Misc-stat-soft.html
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One form of HIV-1 Resistance
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Association test for CCR-5 & HIV resistance Samson et al. Nature 1996 382:722-5Nature 1996 382:722-5
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Association test for CCR-5 & HIV resistance Samson et al. Nature 1996 382:722-5Nature 1996 382:722-5
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But what if we test more than one locus? The future of genetic studies of complex human diseases. RefRef (Note above graphs are active spreadsheets -- just click) GRR = Genotypic relative risk
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Class outline (1) Topic priorities for homework since last class (2) Quantitative exercises so far: psycho-statistics, combinatorials, exponential/logistic, bits, association & multi-hypotheses (3) Project level presentation & discussion (4) Discuss communication/presentation tools Spontaneous chalkboard discussions of t-test, genetic code, non-coding RNAs & predicting deleteriousness of various mutation types.
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