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## powerStudent

version 1.18.0.0 (2.25 KB) by Antonio Trujillo-Ortiz

### Antonio Trujillo-Ortiz (view profile)

Approximate power estimation of a performed Student's t test about mean(s).

Updated 11 Mar 2009

Estimates the approximate statistical power of a performed Student's t test about mean(s). Here, according to Zar (1999) we use the approximation of power by the central cumulative distribution function. It recalls you the statistical result of the test you should have arrived. This power estimation is considered biased, for it is underestimated. However, it is presented for all those interested people.

You can find the exact power estimation on the extpowerStudent m-file.

Inputs:
t - Student's t statistic
df - degrees of freedom
c - specified testing direction [1 = one-tailed(default);2 = two-tailed]
alpha - significance level (default = 0.05)

Outputs:
- Specified direction test
(Statistical result of the test you should have arrived)
- Power

### Cite As

Antonio Trujillo-Ortiz (2020). powerStudent (https://www.mathworks.com/matlabcentral/fileexchange/2907-powerstudent), MATLAB Central File Exchange. Retrieved .

function [Power] = powerStudent(t,df,c,a)
rather than
function [powerStudent] = powerStudent(t,df,c,a)

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Linda Seltzer

It seems that the power is being computed based on the t cumulative distribution function. However, if the null hypothesis is false, isn't the distribution noncentral, with the need to compute a noncentrality parameter? This means that operating curves have to be computed. Is there a Matlab routine somewhere that computes operating curves

florabel cuaya