Re: BinomialDistribution

*To*: mathgroup at smc.vnet.net*Subject*: [mg65224] Re: BinomialDistribution*From*: bghiggins at ucdavis.edu*Date*: Sun, 19 Mar 2006 03:19:02 -0500 (EST)*References*: <dvgsqb$9tf$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Joshua, The integration is being killed by round-off error. Let us examine the distribution function PDF[BinomialDistribution[101,u],26] 942094086221309585483304*(1 - u)^75*u^26 There are some pretty big numbers here. So use exact arithmetic when evaluating the limits of integration by writing Integrate[PDF[BinomialDistribution[101, u], 26], {u, 0, 29/100}] // N 0.00731803 Which as you suspoected should be positive Cheers, Brian Solomon, Joshua wrote: > This makes me feel foolish. > In[1]:=Needs["Statistics`DiscreteDistributions`"] > In[2]:=Plot[PDF[BinomialDistribution[101,u],26],{u,0,0.5},PlotRange->All] > > This gives me a nice, bell-shaped curve, with a minimum of about 0 and a > maximum of about .09. Let's integrate it from 0 to .29. > > In[3]:=Integrate[PDF[BinomialDistribution[101,u],26],{u,0,.29}] > Out[3]=-0.612253 > > How can this be negative?