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?