Question

1.  A psychologist would like to examine the relative effectiveness of three therapy techniques for treating mild phobias.  A sample of N = 15 individuals who display a moderate fear of spiders is obtained.  These individuals are randomly assigned (with n = 5) to each of the three therapies.  The dependent variable is a measure of reported fear of spiders after therapy.  The data are as follows:

    Therapy A                                   Therapy B                                   Therapy C

(Drug Therapy)                (Systematic Desensitization)             (Implosive Therapy)

          8                                                 3                                                    1

          5                                                 3                                                    0                   G = 45

          5                                                 0                                                    1               ∑X² = 221

          7                                                 2                                                    2

          5                                                 2                                                    1

      T = 30                                         T = 10                                           T = 5

     SS = 8                                         SS = 6                                          SS = 2

       a. Do the data indicate that there are any significant differences among the three samples?    

           Test at the .05 level of significance.

       b. Use Tukey’s HSD posttest to determine exactly which treatments are different.  Test at the

            .05 level of significance.

2.  First-born children tend to develop language skills faster than their younger siblings.  One possible explanation for this phenomenon is that first-borns have undivided attention from their parents.  If this explanation is correct, then it is also reasonable that twins should show slower language development than single children and that triplets should be even slower.  The following hypothetical data demonstrate the relationship.  The dependent variable is a measure of language skill at age three for each child.  Do the data indicate any significant differences?  Test with α = .05.  Use the Scheffé test to determine which groups are different.

Single Child                    Twin                    Triplet

         8                                 4                           4

         7                                 6                           4

        10                                7                           7

         6                                 4                           2

         9                                 9                           3

Answer 1

The output of single anova factor is