statistical test for data drawn from t distribution

I have a question about t distribution. I have a set of data and I want to know if they are drawn from a t distribution or not! Can anybody help me how I can do this in Matlab? Thanks

[dpb]

First, how many samples? If n>= ~ 30, the t distribution approaches normal so testing for normality would be essentially the same. There's at least one test for such packaged in Matlab Statistics Toolbox.

[MINA]

n>30. The thing is I'm modeling my data with ARIMA and there I have to choose whether the innovations have Gaussian distribution or t distribution. when I use AIC/BIC criteria to select which model is better, I get a model with innovations drawn from t distribution. Now When I compute the residuals I want to see if they are coming from t-distribution or not. I know that they are not normally distributed- by using kstest.

[dpb]

Then w/ n>30 they won't be t, either, because the two distributions are asymptotically identical. The higher N, the closer and the lesser chances of showing anything different.

[MINA]

@dbp ok I understood. Thanks.

[dpb]

BTW, you can use kstest on the data with a cdf from tcdf; see

doc kstest

for the details. There's lillietest that's more powerful specifically for normality.

But, as noted, for N of 30 or greater the likelihood of there being sufficient difference between T and N is minimal at best to be able for statistical hypothesis test to tell the difference.