T-test

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T-test

andria lan
Hi all, 

What is decision rule of paired T-test that is applied in Weka? Precisely, is it two-tailed, or upper-tailed, or lower-tailed?

Any help would be highly appreciated.

Thanks.
Andria

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Re: T-test

Eibe Frank-3
The Experimenter applies two-tailed paired t-tests. This is implemented in the PairedStats class for the standard t-test and in the PairedStatsCorrected class for the corrected resampled paired t-test.

You can run the PairedStats class directly one some data to try it. Assume we have the following data stored in a file called data.data:

-0.255 -0.324
-0.213 -0.185
-0.190 -0.299
-0.185 -0.144
-0.045 -0.027
-0.025 -0.039
-0.015 -0.264
0.003 -0.077
0.015 -0.017
0.020 -0.169
0.023 -0.096
0.040 -0.330
0.040 -0.346
0.050 -0.191
0.055 -0.128
0.058 -0.182

Then, using bash or similar, we can do this:

cat data.data | java -cp ~/weka-3-8-1/weka.jar weka.experiment.PairedStats
Analysis for 16 points:
                         Column 1         Column 2       Difference
Minimums                  -0.255           -0.346           -0.041 
Maximums                   0.058           -0.017            0.386 
Sums                      -0.624           -2.818            2.194 
SumSquares                 0.1968           0.6799           0.574 
Means                     -0.039           -0.1761           0.1371
SDs                        0.1072           0.1106           0.1349
Prob(differences) 0.001 (sigflag 1)
Correlation       0.233

Cheers,
Eibe

On Thu, Aug 24, 2017 at 2:14 PM, Andria Lan <[hidden email]> wrote:
Hi all, 

What is decision rule of paired T-test that is applied in Weka? Precisely, is it two-tailed, or upper-tailed, or lower-tailed?

Any help would be highly appreciated.

Thanks.
Andria

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Send posts to: [hidden email]
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