A firm is studying the effect of work shift and parts supplier on its defect rate (dependent variable is defects per 1000). The resulting ANOVA results are shown below (some information is missing). $$\begin{array} { | l | c | c | c | c | c | }
\hline \text { Source } & \text { Sum of Squares } & d f & \text { Mean Square } & F & \text { P-Value } \
\hline \text { Shift } & 704.07 & 2 & 352.04 & 11.93 & 0.001 \
\hline \text { Supplier } & 19.6 & & 9.8 & 0.33 & 0.72 \
\hline \text { Shift*Supplier } & 430.75 & 4 & 107.69 & 3.65 & 0.014 \
\hline \text { Error } & 1062.05 & 36 & 29.5 & & \
\hline \text { Total } & 2216.47 & 44 & & & \
\hline
\end{array}$$ How many suppliers were there?
A)1
B)2
C)3
D)4

Question

A firm is studying the effect of work shift and parts supplier on its defect rate (dependent variable is defects per 1000). The resulting ANOVA results are shown below (some information is missing). $$\begin{array} { | l | c | c | c | c | c | } 
\hline \text { Source } & \text { Sum of Squares } & d f & \text { Mean Square } & F & \text { P-Value } \
\hline \text { Shift } & 704.07 & 2 & 352.04 & 11.93 & 0.001 \
\hline \text { Supplier } & 19.6 & & 9.8 & 0.33 & 0.72 \
\hline \text { Shift*Supplier } & 430.75 & 4 & 107.69 & 3.65 & 0.014 \
\hline \text { Error } & 1062.05 & 36 & 29.5 & & \
\hline \text { Total } & 2216.47 & 44 & & & \
\hline
\end{array}$$ How many suppliers were there?
A)1
B)2
C)3
D)4

Quizplus · Accepted Answer

The degrees of freedom for the supplier is calculated as the number of suppliers minus one. Since the total degrees of freedom is 44 and the degrees of freedom for error is 36, the degrees of freedom for the supplier can be found by subtracting the degrees of freedom for shift (2) and interaction (4) from the total, which gives 2. Therefore, there were 3 suppliers (2 + 1 = 3).

A Firm Is Studying the Effect of Work Shift and Parts