 Computing t for Independent Samples (pooled variance)

 Variables to Enter Input Column Variance for Group 1 S21 Variance for Group 2 S22 Mean for Group 1 Mean1 Mean for Group 2 Mean2 Number of participants for Group 1 n1 Number of participants for Group 2 n2 Variables below list elements of the t test computations Values below are computed for you. Pooled Variance S2pooled= Standard Error of Mean 1 S2M1= Standard Error of Mean 2 S2M2= S2Difference= SDifference= t=

To test the concept: “are the two means significanctly different ?” ; which is a test of the null hypothesis that Ho: mean1 = mean2, we simply compare the “t score” observed in the table above against the “t score ” critical , which we take from a “t table ” based on the degrees of freedom of dftotal= (n1 - 1) + (n2 - 1) for the two independent sample test, at a probability level of p<0.05 is available in any t distribution table. If the “t score” observed is greater than the “t score ” critical then we reject the null hypothesis and state that the sample mean is significantly different than the population mean. Click here to return to the Webulator Menu Page