Log transformation  

If you selected the Log transformation option, the program performs the calculations on the logarithms of 

the observations, but reports the back transformed summary statistics.  

For the One sample t test, the difference between sample mean and test value, with 95% confidence 

interval, are given on the log transformed scale.  

Next, the results are transformed back and the interpretation is as follows: the back transformed difference 

of the logs is ratio of the sample mean / test value on the original scale. 

Independent samples t test 

The independent samples t test is used to compare the means of two independent samples. 

Required input 

Select the variables for sample 1 and sample 2.  Use the 

  button to select variables and selection 

criteria in the variables list.   

Options 

  Logarithmic transformation: select this option if the data are positively skewed. 

  Correction for unequal variances: allows to select the t test (assuming equal variances) or the t test 

corrected for unequal variances (Welch test).  With the option "Automatic" the software will select the 

appropriate test based on the F test (comparison of variances).   

Results 

After you have clicked the 

OK

 button, the program displays the summary statistics of the two samples, 

followed by the statistical tests. 

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