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## test-t

version 2.0 (34.2 KB) by

Calculate the Student t Test for unequal or equal samples size, unpaired or paired samples.

Updated

Student's t test for unpaired or paired samples.
This file is applicable for equal or unequal sample sizes; for paired or
unpaired samples. When the test is unpaired, the Fisher-Snedecor F-test is
performed to assess the equality of variance. If variances are not equal,
Satterthwaite's approximate t test is performed.
Syntax: TESTT(X1,X2,TST,ALPHA,TAIL)

Inputs:
X1 and X2 - data vectors (mandatory).
TST - unpaired (0) or paired (1) test (default = 0).
ALPHA - significance level (default = 0.05).
TAIL - 1-tailed test (1) or 2-tailed test (2). (default = 1).
Outputs:
- t value.
- degrees of freedom.
- Confidence interval of means difference (for paired test)
- p-value
- Power
Example:
X1=[77 79 79 80 80 81 81 81 81 82 82 82 82 83 83 84 84 84 84 85 ...
85 86 86 87 87];

X2=[82 82 83 84 84 85 85 86 86 86 86 86 86 86 86 86 87 87 87 88 ...
88 88 89 90 90];

Calling on Matlab the function: testt

FISHER-SNEDECOR F-TEST FOR EQUALITY OF VARIANCES

F DF_numerator DF_denominator p_value
______ ____________ ______________ _______

1.5379 24 24 0.29861

--------------------------------------------------------------------------------
Variances are equal
--------------------------------------------------------------------------------

STUDENT'S T-TEST FOR UNPAIRED SAMPLES

t DF tail p_value Power
______ __ ____ _________ _______

5.2411 48 1 1.765e-06 0.99958

STATS=TESTT(...) returns a structure with all test(s) statistics

Created by Giuseppe Cardillo
giuseppe.cardillo-edta@poste.it

To cite this file, this would be an appropriate format:
Cardillo G. (2006). Student t-Test for unpaired or paired samples.
http://www.mathworks.com/matlabcentral/fileexchange/12699

Ben

Thanks

john Chandler

### john Chandler (view profile)

can the p-value, etc be passed onto variables?

Giuseppe Cardillo

### Giuseppe Cardillo (view profile)

You have partially right. I have fixed the bug and uploaded the new file. Thank you very much!

Rune W Berg

### Rune W Berg (view profile)

There's a small bug in the procedure that prevents you chose 2-tailed test. Its in line 109.

As far as i can see you need to change it to:

109: if tail ~= 0 && tail ~= 1 && tail ~= 2 %check if tst is 0 or 1 or 2

this m file is good,easy and useful.many thanks Giuseppe

Diego García Bascuñán

If you get the powerStudent, testt works. It's fantastic do it so easily!!!

Giuseppe Cardillo

The file powerStudent is not included because is not a file of mine. As highlighted in the File Details this is a file of Antonio Trujillo Ortiz (file ID: 2907) that you can download.

ifan lin

This m file calls another function: powerStudent, which is not included.