how do you test in spss for interaction between the interaction term between COPD group and age at rehab. if model is Y = 0 + 1*X1 + 2*X2 + 3*X1*X2 + and null hypothesis is The null hypothesis (H0) would be that there is no interaction between the COPD group and age at rehab, i.e., 3 = 0. The alternative hypothesis (H1) would be that there is an interaction between the COPD group and age at rehab, i.e., 3 0. If we reject the null hypothesis, it implies that the interaction term is significant, meaning the effect of the COPD group on the dependent variable depends on the age at rehab. If we accept the null hypothesis, it implies that there is no interaction effect. also what is your independent variable