Does the Environment Affect Bird Weight? Researchers Measured the Weight

Multiple Choice

Does the environment affect bird weight? Researchers measured the weight (in grams) of male and female adult finches that were either raised in an aviary or caught in the wild. This observational study does not have a balanced design, particularly because finches caught in the wild were more difficult to obtain. A total of 52 finches were studied. A partial ANOVA table is provided below, along with an interaction plot displaying the group means.
​
$$\begin{array}{l}\begin{array} { l r r r } \text { Factor } & \text { Type } & \text { Levels } & \text { Values } \\\text { malefemale } & \text { fixed } & 2 & f , m \\\text { origin } & \text { fixed } & 2 & \text { aviary, wild }\end{array}\\\\\text { Analysis of Variance for bird weight }\\\\\begin{array} { l r r r r r } \text { Source } & \text { DF } & \text { SS } & \text { MS } & \text { F } & \text { P } \\\text { Malefemale } & 1 & 10.844 & 10.844 & & \\\text { origin } & 1 & 19.607 & 19.607 & & \\\text { interaction } & 1 & 0.340 & 0.340 & & \\\text { Error } & 48 & 125.140 & 2.607 & &\end{array}\end{array}$$ S = 1.61465 R-Sq = 23.88% R-Sq(adj) = 19.12%
The researcher has determined there is no significant interaction effect, so we may proceed to analyze the main effects of sex and origin. Using a significance level of 0.05, what do the results suggest about the main effects of sex and origin?

A) Sex affects mean weight significantly in finches, but origin does not.
B) Origin affects mean weight significantly in finches, but sex does not.
C) In finches, sex affects mean weight significantly, and origin affects mean weight significantly, but the two influences work independently.
D) Sex affects mean weight significantly, and origin affects mean weight significantly, but the influence of origin is different for male and for female finches.