Questions Refer to Table 11-2 ONEWAY ANOVA: SMOKING by AGE (CORR SAMP)

Questions refer to Table 11-2. In this study, 10 children completed a survey regarding their impressions of smokers at age 8 and then again at age 10 and 12. Scores could range from 1 (extreme negative impression of smokers) to 20 (extreme positive impression of smokers) .

Table 11-2
$\begin{array} { c c c c c } \text { GROUP } & \mathrm { N } & \text { MEAN } & \text { STD DEV } & \text { STD ERROR } \\ 1 \text { (AGE 8) } & 10 & 9.70 & 5.89 & 1.86 \\ 2 \text { (AGE 10) } & 10 & 10.40 & 5.58 & 1.76 \\ 3 \text { (AGE 12) } & 10 & 11.80 & 5.94 & 1.88 \end{array}$


ONEWAY ANOVA: SMOKING by AGE (CORR SAMP)


$\begin{array} { l c c c r r } & \text { SUM OF } & \text { MEAN } & & \\ \text { SOURCE } & \text { SQUARES } & \text { DF } & \text { SQUARES } & \text { F RATIO } & \text { PROB. } \\ \text { AGE } & 22.87 & 2 & 11.43 & 6.76 & .006 \\\text { SUBJECTS } & 879.63 & 9 & 97.74 & 34.71 & .000 \\\text { WITHIN CELLS } & 30.47 & 18 & 1.69 & & \\\text { TOTAL } & 932.97 & 29 & & & \end{array}$


POST HOC TEST: Tukey-HSD with significance level .05
* Indicates significant differences shown for pairings
$\begin{array} { l l l } \mathrm { G } & \mathrm { G } & \mathrm { G } \\ \mathrm { r } & \mathrm { r } & \mathrm { r } \\ \mathrm { p } & \mathrm { p } & \mathrm { p } \\ 1 & 2 & 3 \end{array}$


$\begin{array}{ll}\text { Mean } & \mathrm{AGE}\\9.70 & \text { Grp } 1 \\10.40 & \text { Grp 2 } \\11.80 & \text { Grp } 3\end{array}$
-Consult Table 11-2. Why are the degrees of freedom for the age variable equal to 2?

A) Because there are two levels of the independent variable.
B) Because there are three levels of the independent variable.
C) Because there are two significant differences.
D) Because the formula for df between is always 1 + 1.