8.30 Checking Conditions for Body Mass Gain The mice in the study had body mass measured through- out the study. Computer output showing body mass gain (in grams) after 4 weeks for each of the three light conditions is shown, and a dotplot of the data is given in Figure 8.6. Level DM 393 LD LL N 10 8 9 Mean 7.859 5.926 11.010 StDev 3.009 1.899 2.624 (a) In the sample, which group of mice gained the most, on average, over the four weeks? Which gained the least? (b) Do the data appear to meet the requirement of having standard deviations that are not dramat- ically different? (c) The sample sizes are small, so we check that the data are relatively normally distributed. We see in Figure 8.6 that we have no concerns about the DM and LD samples. However, there is an out- lier for the LL sample, at 17.4 grams. We proceed as long as the z-score for this value is within +3. Find the z-score. Is it appropriate to proceed with ANOVA? (d) What are the cases in this analysis? What are the relevant variables? Are the variables cate- gorical or quantitative?