Re: fit a BinomialDistribution to exptl data?
- To: mathgroup at smc.vnet.net
- Subject: [mg80503] Re: fit a BinomialDistribution to exptl data?
- From: Ray Koopman <koopman at sfu.ca>
- Date: Thu, 23 Aug 2007 06:25:12 -0400 (EDT)
- References: <fagso0$8ad$1@smc.vnet.net>
On Aug 22, 1:39 am, Gordon Robertson <agrobert... at telus.net> wrote:
> Given a list of data values, or a list of x-y data points for
> plotting the data as an empirical distribution function, how can I
> fit a BinomialDistribution to the data? The help documentation for
> FindFit shows examples in which the user indicates which function
> should be fit (e.g. FindFit[data, a x Log[b + c x], {a, b, c}, x]),
> and I've been unable to find an example in which a statistical
> distribution is being fit to data. Mathematica complains when I try the
> following with an xy list of data that specified an EDF: FindFit
> [xyvals, CDF[BinomialDistribution[n, pp], k], {n, pp}, k].
>
> G
> --
> Gordon Robertson
> Canada's Michael Smith Genome Sciences Centre
> Vancouver BC Canada
Use the same mean & variance, m & v, to get initial estimates of n &
p:
{m == n*p, v == n*p*(1-p)} <==> {n == m^2/(m-v), p == (m-v)/m}