BigAlOz
11-14-2013, 08:38 PM
I am trying to work out how to use the gammadist to calculate the Chi-Squared probability.
Basically I have
1. A Least squares adjustment
2. I have the degrees of freedom (measurements - unknowns)
3. The adjustmnet calculates the variance factor (VF)
4. Need to do Chi squared test on the Variance factor
- Test that the VF is statistically within the expected probability
- Test the VF againt unity at the 95% probability
I tried this
Gammadist gm(m-u,0.5)
// m-u = degrees of freedom
// 0.5 used as the text suggested this
x = gm.p(VF)
// i am assuming this should be a number between 0 and 1
// *100 = %
y = gm.cdf(VF)
// don't know what this might mean
Anyway I don't get reasonable values using the above.
Could somebody please explain how this function should be called.
Thanks in Advance
Alan
Basically I have
1. A Least squares adjustment
2. I have the degrees of freedom (measurements - unknowns)
3. The adjustmnet calculates the variance factor (VF)
4. Need to do Chi squared test on the Variance factor
- Test that the VF is statistically within the expected probability
- Test the VF againt unity at the 95% probability
I tried this
Gammadist gm(m-u,0.5)
// m-u = degrees of freedom
// 0.5 used as the text suggested this
x = gm.p(VF)
// i am assuming this should be a number between 0 and 1
// *100 = %
y = gm.cdf(VF)
// don't know what this might mean
Anyway I don't get reasonable values using the above.
Could somebody please explain how this function should be called.
Thanks in Advance
Alan