TABLE 14-11
A weight-loss clinic wants to use regression analysis to build a model for weight loss of a client (measured in pounds) .Two variables thought to affect weight loss are client's length of time on the weight-loss program and time of session.These variables are described below:
Y = Weight loss (in pounds)
X₁= Length of time in weight-loss program (in months)
X₂ = 1 if morning session,0 if not
Data for 25 clients on a weight-loss program at the clinic were collected and used to fit the interaction model:
Y = β₀ + β₁X₁ + β₂X₂ + β₃X₁X₂ + ε
Output from Microsoft Excel follows:
-Referring to Table 14-11,in terms of the βs in the model,give the mean change in weight loss (Y) for every 1 month increase in time on the program (X₁) when not attending the morning session.

Question

TABLE 14-11
A weight-loss clinic wants to use regression analysis to build a model for weight loss of a client (measured in pounds) .Two variables thought to affect weight loss are client's length of time on the weight-loss program and time of session.These variables are described below:
Y = Weight loss (in pounds)
X₁= Length of time in weight-loss program (in months)
X₂ = 1 if morning session,0 if not
Data for 25 clients on a weight-loss program at the clinic were collected and used to fit the interaction model:
Y = β₀ + β₁X₁ + β₂X₂ + β₃X₁X₂ + ε
Output from Microsoft Excel follows:

-Referring to Table 14-11,in terms of the βs in the model,give the mean change in weight loss (Y) for every 1 month increase in time on the program (X₁) when not attending the morning session.

Quizplus · Accepted Answer

According to the model, the coefficient for X₁ (length of time on the program) is β₁, which represents the mean change in weight loss for every 1 month increase in time on the program, holding all other variables constant. Since we are only interested in the effect when not attending the morning session, we do not need to consider the interaction term (X₁X₂) or the coefficient for X₂. Similarly, we do not need to consider the interaction between length of time on the program and X₂ (X₁X₂) or the coefficient for X₃. Thus, the only coefficient that is relevant is β₁.

TABLE 14-11 A Weight-Loss Clinic Wants to Use Regression Analysis to Build