Question: If you have k groups why do you only need
If you have k groups, why do you only need k-1 dummy variables to represent group membership? Why is it impossible to include k dummy variable as predictors in a regression when you have k groups?
Answer to relevant QuestionsHow does orthogonal coding of dummy variables differ from dummy and effect coding? Write out an equation to represent a 2 x 2 factorial ANOVA (make up your own variable names); include an interaction term in the equation. What information should be included in the report of a hierarchical or statistical multiple regression (i.e., a series of regressions with one variable or a group of variables entered in each step)? What kind of reasoning would justify a decision to enter some variables earlier than others in a hierarchical regression analysis? Refer to Figure 16.1. If a, b, and a*b are all statistically significant (and large enough to be of practical or clinical importance), and c’ is not statistically significant and/or not large enough to be judged ...
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