Re: [R] Fitting gamma and exponential Distributions with fitdist

2011-04-28 Thread vioravis
I tried using JMP for the same and get two distinct recommendations when using the unscaled values. When using the unscaled values, Log Normal appears to be best fit. fitdist in R is unable to provide a fit in this case. Compare Distributions ShowDistributionNumber of Parameters -2

Re: [R] Fitting gamma and exponential Distributions with fitdist

2011-04-28 Thread vioravis
Joshua, thanks for your reply. I have tried out the following scaling and it seems to work fine: scaledVariable <- (test-min(test)+0.001)/(max(test)-min(test)+0.002) The gamma distribution parameters are obtained using the scaled variable and samples obtained from this distributions are scaled

Re: [R] Fitting gamma and exponential Distributions with fitdist

2011-04-27 Thread Prof Brian Ripley
On Wed, 27 Apr 2011, Joshua Wiley wrote: Hi, I am not incredibly knowledgeable about gamma distributions, but looking at your data, you have a tiny mean:variance ratio, which, I believe, means that the bulk of the distribution will be near 0 and you may run into computational problems (again I

Re: [R] Fitting gamma and exponential Distributions with fitdist

2011-04-27 Thread Joshua Wiley
Hi, I am not incredibly knowledgeable about gamma distributions, but looking at your data, you have a tiny mean:variance ratio, which, I believe, means that the bulk of the distribution will be near 0 and you may run into computational problems (again I think. I would gladly be corrected). This

Re: [R] Fitting gamma and exponential Distributions with fitdist

2011-04-27 Thread vioravis
There was a small error in the data creation step and have fixed it as below: test <- c(895.1358,2915.7447,335.5472,1470.4022,194.5461,1814.2328, 1056.3067,3110.0783,11441.8656,142.1714,2136.0964,1958.9022, 891.89,352.6939,1341.7042,167.4883,2502.0528,1742.1306, 837.1481,867.8533,3590.4308,1125