# is.gamma: is.gamma In DnE: Distribution and Equation

## Description

judge if the data obeys gamma distribution.

## Usage

 `1` ```is.gamma(x, m, a, a0 = NULL, b0 = NULL) ```

## Arguments

 `x` data `m` the number of intervals you want to divide the data in, defualt value is 10 `a` confidence level `a0` represent the first parmeter in gamma distribution `b0` represent the second parmeter in gamma distribution

## Details

Given a set of observations from a certain distribution, this function is used to test whether the observations are from a distribution of gamma distribution or not. Usually, to ensure the function works well, the sample size needs to be large enough, i.e. the result will be stable if the sample size is larger than 100. The gamma distribution mentioned in this function is the one with mean a/b and variance a/b^2, where a is the first parameter and b is the second parameter in gamma distribution. The function will work better if the number of intervals you choose to divide the data in is between 10 and 20. This number cannot excess the number of given oberservations.

## Value

if the data possibly obeys the distribution, return a value named qchisq which represents the possibility. The larger qchisq is, the larger the possibility will be; else return -1.

## Note

please play attention to the definition of parameters in our functions.

## Author(s)

JunYao Chen, CuiYi He, BoXian Wei

## References

ROBERT V. HOGG/ALLEN T. CRAIG (Fifth Edition) Introduction Mathematical Statistics.

`is.dt` , `DnE-package`
 ```1 2 3 4 5 6``` ```require(stats) examplecheck<-rgamma(100,2,4) is.gamma(examplecheck,10,0.05) ##---- Should be DIRECTLY executable !! ---- ##-- ==> Define data, use random, ##-- or do help(data=index) for the standard data sets. ```