For the data set A Find the multiple regression line Y B0
For the data set:
A. Find the multiple regression line, Y = B0 + B1*X1 + B2*X2 + B3*X1*X2.
B. Is the interaction term significant?
| X1 | X2 | Y | 
| 5.66 | 3.99 | (10.69) | 
| 5.32 | (3.39) | 15.41 | 
| 7.01 | 2.07 | 7.21 | 
| 6.90 | 3.74 | (2.93) | 
| 0.97 | 4.27 | 23.13 | 
| 5.66 | 4.32 | (15.06) | 
| 1.21 | (0.77) | 6.78 | 
| 9.85 | (4.20) | 54.04 | 
| 5.54 | (0.97) | (2.96) | 
| 5.08 | (3.38) | 11.83 | 
| 5.39 | (4.59) | 23.43 | 
| 0.74 | 1.78 | 25.10 | 
| 9.82 | (1.84) | 32.18 | 
| 8.23 | 2.09 | 24.45 | 
| 5.18 | (3.11) | 38.02 | 
| 4.33 | 1.94 | 1.87 | 
| 1.20 | (2.61) | 24.15 | 
| 6.61 | 2.94 | (5.03) | 
| 5.89 | (3.60) | 35.00 | 
| 4.69 | 4.35 | (26.09) | 
| 8.64 | (3.95) | 31.15 | 
| 9.23 | (0.19) | 11.86 | 
| 0.87 | 0.53 | 19.69 | 
| 8.79 | (3.80) | 9.98 | 
| 0.01 | (2.94) | (0.17) | 
| 7.07 | 0.79 | 3.60 | 
| 3.20 | (2.02) | 1.93 | 
| 6.43 | 0.83 | 5.85 | 
| 0.18 | 2.60 | 24.93 | 
| 4.46 | 2.48 | 5.72 | 
| 6.90 | (0.61) | 19.36 | 
| 0.24 | (4.97) | (7.45) | 
| 4.90 | 0.20 | (19.22) | 
| 2.68 | 3.66 | (5.40) | 
| 0.40 | 0.17 | (11.95) | 
| 7.22 | 2.52 | (16.36) | 
| 6.26 | 4.88 | (20.34) | 
| 7.52 | (2.37) | (13.20) | 
| 7.37 | (4.03) | 37.51 | 
| 0.07 | 1.96 | 4.89 | 
| 1.30 | 0.95 | 50.52 | 
| 8.13 | (3.49) | 18.98 | 
| 8.96 | (3.83) | 55.65 | 
| 5.13 | 0.15 | 6.62 | 
| 9.39 | 3.37 | (30.14) | 
| 0.75 | 2.23 | 17.68 | 
| 1.46 | (1.47) | 28.36 | 
| 3.95 | (0.42) | 10.17 | 
| 1.76 | (4.42) | (0.98) | 
| 5.75 | 2.24 | (14.38) | 
Solution
Running this regression in SPSS, we get the following regression table
           Coefficients(a)
        Unstandardized Coefficients       Standardized Coefficients
 Model B Std. Error Beta t Sig
(Constant)   22.714    6.459     3.516   .001
    X1 -2.194   1.229 -.485 -1.785   .081
    X2 -4.206   2.345 -.441 -1.794   .079
    X12 1.258   .422 1.084   2.981   .005
 a. Dependent Variable: Y
From above table, regression line is Y=22.714 - 2.194 X1 - 4.206 X2 + 1.258 X1X2
We see that the p value for interaction effect is 0.005 which is less than 0.05, so we reject the null hypothesis that coefficient is insignificant and accept the alternative that interaction effect is significant.
Interaction term is significant.


