bug in rbinom? (PR#1190)
Peter Dalgaard BSA <p.dalgaard@biostat.ku.dk> writes:
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.
This seems not to be present in the original Fortran (once I got it to compile properly -- it requires -fno-automatic) so there has to be a transcription error somewhere. I'll be darned if I can find it, though.
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 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-devel-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._