[Rd] bug in rbinom? (PR#1190)
Peter Dalgaard BSA
p.dalgaard@biostat.ku.dk
02 Dec 2001 01:55:16 +0100
viele@ms.uky.edu writes:
> I was simulating the central limit theorem in class,
> but found that repeated use of
>
> mean(rbinom(100000,500,0.4))
>
> resulted in values less than 200 (the expected mean), for example
>
> > mean(rbinom(100000,500,0.4))
> [1] 199.0294
> > mean(rbinom(100000,500,0.4))
> [1] 199.1077
> > mean(rbinom(100000,500,0.4))
> [1] 199.0668
> and so on.
>
> I did this 1000 times and found the results to be distributed
> approximately N(199.0787,s=0.036). The standard deviation
> is pretty accurate, but the mean is significantly off from 200.
I see the same thing on Linux. Looks like it needs checking against
the original CACM algorithm.
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk) FAX: (+45) 35327907
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