Instruction 13 $\begin{array}{ll}\text { ANOVA }\\ F=5.41118 & \text { Significance } F= \\& 0.040201\end{array}$

Instruction 13.8
A weight-loss clinic wants to use regression analysis to build a model for weight-loss of a client (measured in kilograms) . Two variables thought to effect 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 kilograms)
X₁ = Length of time in weight-loss program (in months)
X₂ = 1 if morning session, 0 if not
X₃ = 1 if afternoon session, 0 if not (Base level = evening session)
Data for 12 clients on a weight-loss program at the clinic were collected and used to fit the interaction model:
Y = ?0 + ?₁X₁ + ?₂X₂ + ?₃X₃ + ?₄X₁X₂ + ?₅X₁X₃ + ?
Partial output from Microsoft Excel follows:
$\begin{array}{ll}\text { Regression}\\\text { Statistics}\\ \text { MultipleR } & 0.73514 \\\text { R Square } & 0.540438 \\\text { Adjusted R Square } & 0.157469 \\\text { Standard Error } & 12.4147 \\\text { Observations } & 12\end{array}$

$\begin{array}{ll}\text { ANOVA }\\ F=5.41118 & \text { Significance } F= \\& 0.040201\end{array}$


$\begin{array}{lllll}&\text { Coeff }&\text { StdError }&\text { t Stat }&\text { p-value }\\\text { Intercept } & 0.089744 & 14.127 & 0.0060 & 0.9951 \\\text { Length }\left(X_{1}\right) & 6.22538 & 2.43473 & 2.54956 & 0.0479 \\\text { Morn Ses }\left(X_{2}\right) & 2.217272 & 22.1416 & 0.100141 & 0.9235 \\\text { Aft Ses }\left(X_{3}\right) & 11.8233 & 3.1545 & 3.558901 & 0.0165 \\\text { Length* Morn Ses } & 0.77058 & 3.562 & 0.216334 & 0.8359 \\\text { Length*Aft Ses } & -0.54147 & 3.35988 & -0.161158 & 0.8773\end{array}$
-Referring to Instruction 13.8,what is the experimental unit for this analysis?

A) A client on a weight-loss program.
B) A month.
C) A morning, afternoon, or evening session.
D) A clinic.