Question

A researcher is interested in the effects of practice on accuracy of signal-detection
task. Seven participants were tested in three conditions: no practice, after 1 hour
practice and after 3 hours practice. Each person participated in all three
conditions. The following data indicate how many signals were accurately detected at
each level. Test the claim that practice improves detection at alpha = 0.05

No Practice            1 Hour              3 Hour

         3                      4                        7
         4                      4                        5
         2                      3                        4
         1                      3                        6
         3                      6                        7
         3                      4                        6
         2                      3                        5

  Mean=2.57      Mean=3.86       Mean=5.71

Grand Mean, round to four decimals=

SSSubjects, round to four decimals =

Answer 1

The statistical software output for this problem is:

Hence,

Grand mean = (2.57 + 3.86 + 5.71)/3 = 4.0467

SSsubjects = SS Columns = 34.9524