A two-variable model involving one quantitative explanatoryvariable and one categorical (binary) explanatory variable (and nointeraction), results in two regression lines that are:

A.     Always parallel.

B.     Could be parallel but, dependingon the data, may not.

C.      Never parallel.

D.     Always horizontal.

The two methods of including a binary categorical variable in aregression model are to use indicator coding or effect coding. Forindicator coding in the two-variable model (withno interaction):

A.     The binary variable is coded(-1,1) and the coefficient for the binary variable in thecorresponding regression equation is the difference between the twogroup means.

B.     The binary variable is coded(-1,1) and the coefficient for the binary variable in thecorresponding regression equation is the difference between one ofthe group means and the least-squares mean (the overall mean).

C.      The binary variable iscoded (0,1) and the coefficient coefficient for the binary variablein the corresponding regression equation is the difference betweenthe two group means.

D.     The binary variable is coded(0,1) and the coefficient for the binary variable in thecorresponding regression equation is the difference between one ofthe group means and the least-squares mean (the overall mean).