Methods
Manual: ttest  hand calculation 
for independent samples* 



4. Use the following formula to calculate the tratio. 

=
sum the following scores 



5. Find the probability value (p) associated with the obtained tratio of 2.19.  


For this example, t = 2.40, df = 17. The obtained value of 2.40 exceeds the cutoff of 2.11 shown on the table at the .05 level. Therefore, p <.05. In a report the result is shown as t(17) = 2.40, p<.05. * If you have matched samples (i.e., the two sets of scores are from the same individuals or from matched groups), you must use a different formula. See ttest for paired samples. 