A psychological experiment was performed to determine whether in problem-solving dyads containing one male and one female, "influencing" behavior depended on the sex of the experimenter. The problem for each dyad was a strategy game called "Rope a Steer," which required 20 separate decisions about which way to proceed toward a defined goal on a game board. For each subject in the dyad, a verbal-influence activity score was derived as a function of the number of statements made by the subject to influence the dyad to move in a particular direction. The difference in verbal-influence activity scores within a dyad was denoted as the variable VIAD, which was then used as the dependent variable in an ANACOVA designed to control for the effects of differing IQ scores of the male and female in each dyad. The relevant data are given in the following tables.
a. State an ANACOVA model appropriate for these data.
b. Determine adjusted mean VIAD scores for each group, and compare these to the unadjusted means for each group.
c. Test whether the adjusted mean scores differ significantly.
d. Find a 95% confidence interval for the true difference in adjusted mean scores.

Regression of Viad on IQM, IQF, and Z

Regression of Viad on IQM, IQF, Z, IQM × Z, and IQF × Z

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Group 1: Male Experimenter (Z 0) 915 15 VIAD IQM IQr 13 -10-4 115 112 106 123 125 105 15 122 138 110 100 110 108 35 5 112 1 132 135 126 5 841 Group 2: Female Experimenter (Z = 1) VIAD 85 27 15 10 -3 10 120 130 110 113 102 141 120113114102 IQA 141 128 04 98 106 130 128 105 107 111 DESCRIPTIVE STATISTICS Standard Uncorrected SS Variance Deviation Variable Intercept QM QF Sum Mean 20.00000 100000 2336.00000 116.80000 2352.00000 117 60000 050000 0,70000 20,00000 275060 116.58947 10 79766 279924 175.200001323631 10.00000 10.00000 0 28316 051 VIAD 14.00000 1518.00000 937895 8.90949 Portion of output omitted] PARAMETER ESTIMATES Parametor Standard t Value Pr> t Variable DF Estimate Intercept İQM QF Error 250 0.0238 1 0.69301 0.19389 3.57 0.0025 176 0 0974 166 0.1167 44.59001 17.85879 0 28109 0.15967 5.19610 3 13292 ANALYSIS OF VARIANCE Sum of DFI Squares Mean Pr> F Source Modei Error Corrected Total Square F Value 275 0.0623 746.73852 781.46148 1508.20000 149.34770 54 54.39011 14 19 PARAMETER ESTIMATES Parameter Standard Variable Intercept IQM IQF DFI Estimate Error t Value Pr> Type I SS 9.80000 -0.73495 0.31358 -2.34 0.0344 502 25850 1.27 0.2234 109 79250 0,16 0.8774 131.46715 0.06709 3.15327 43.99054 29 67269 1.48 0.1604 0.32723 6.03875 3843473 0.07613 0.25688 0.41737 0.34325-024 08132 0.18 0.8579 QFz -0.08265