Refer to the following partial ANOVA results from Excel (some information is missing). $$\begin{array} { | l | c | c | c | c | }
\hline \text { Source of Variation } & S S & d f & M S & F \
\hline \text { Between groups } & & & 210.2778 & \
\hline \text { Within groups } & 1483 & & 74.15 & \
\hline \text { Total } & 2113.833 & & & \
\hline
\end{array}$$ The number of treatment groups is:
A)4.
B)3.
C)2.
D)1.

Question

Refer to the following partial ANOVA results from Excel (some information is missing). $$\begin{array} { | l | c | c | c | c | } 
\hline \text { Source of Variation } & S S & d f & M S & F \
\hline \text { Between groups } & & & 210.2778 & \
\hline \text { Within groups } & 1483 & & 74.15 & \
\hline \text { Total } & 2113.833 & & & \
\hline
\end{array}$$ The number of treatment groups is:
A)4.
B)3.
C)2.
D)1.

Quizplus · Accepted Answer

The number of treatment groups can be determined by adding 1 to the degrees of freedom (df) for the "Between groups" since df is calculated as the number of groups minus 1. Given the total df is the sum of "Between groups" df and "Within groups" df, and knowing the "Within groups" df and the total df, we can calculate the "Between groups" df. The total df is 2113.833 - 1483 = 630.833 (this calculation is incorrect; it should be based on SS, not df, and is not needed for finding the number of groups). The correct approach is to find the "Between groups" df from the given information and then add 1 to find the number of groups. Since the "Within groups" df is not directly used to find the number of groups, the explanation involves calculating the "Between groups" df from the total df minus "Within groups" df, then adding 1 to find the number of groups. Given the missing steps and incorrect focus, the correct calculation involves using the given SS and MS to find df for "Between groups" and then deducing the number of groups.

Refer to the Following Partial ANOVA Results from Excel (Some