>>>>> "Amit" == Amit Kabiri <[EMAIL PROTECTED]>
>>>>> on Sat, 03 Dec 2005 18:43:28 +0200 writes:
Amit> If I have a Uniform distribution to check, How can I
Amit> use visual fits? Can I also use in some way the
Amit> qqnorm?
yes, in *some* way:
U <- runif(100)
plot(sort(U)) # is already sufficient
visually
plot(ppoints(U), sort(U)) ; abline(1,1, lty = 3) # is a bit nicer
Amit> Thanks
Amit> -----Original Message----- From:
Amit> [EMAIL PROTECTED]
Amit> [mailto:[EMAIL PROTECTED] On Behalf Of
Amit> Elizabeth Lawson Sent: Friday, November 18, 2005 8:06
Amit> PM To: David Zhao Cc: [email protected]
Amit> Subject: Re: [R] Goodness fit test HELP!
Amit> What about trying a qqplot to see how the distribution
Amit> fits...
Amit> For the normal distribution thta is very stright
Amit> forward, use qqnorm.
Amit> To test gamma distribtution (or any other) do some
Amit> thing like this
Amit> n<-length(data) for(i in 1:n){ prob<-(i-1/3)/(n1/3)
Amit> }
Amit>
quantiles<-qgamma(prob,shape=mean(data)/var(data),scale=var(data)/mean(data)
Amit> }
Amit> qqplot(data,quantiles)
Amit> If the distribution is a good for, you should a
Amit> stright line, like wiht a qqnorm plot!
Amit> Good luck!!
Amit> Elizbaeth Lawson
Amit> David Zhao <[EMAIL PROTECTED]> wrote: Hi there,
Amit> I'm a newbie, plesae bear with me. I have a dataset
Amit> with about 10000 ~ 30000 data points. Would like fit
Amit> to both Gamma and Normal distribution to see which one
Amit> fits better. How do I do this in R? Or I could do a
Amit> normality test of the data, if it's normal, I then
Amit> will do a normal fit, otherwise, a gamma fit. But
Amit> again, I don't know how to do this either. Please
Amit> help!
Amit> David
Amit> [[alternative HTML version deleted]]
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