12.2 Bronchial reactivity.
(A) Explore the data with side-by-side boxplots. Not yet done.
(B) Test the means for a difference with a one-way ANOVA procedure. Descriptive statistics are
n Mean StdDev
SO2 5 18.840 9.692
NO 6 6.617 3.945
O2 4 4.975 3.409
Total 15 10.253
12.4 Fever reduction. Conduct an ANOVA.
Interpret your results. The ANOVA show the differences to be significant.
12.6 Maternal smoking 1. Stemplots were not requested by are helpful in getting organized.
4| 5| 6| 29 7| 45 8| 3 9| 2 �10 Group 1 (non-smokers) |
4| 5|8 6| 7| 138 8| 2 9| �10 Group 2 (Ex-smokers) |
4|7 5|89 6|22 7| 8|3 9| �10 Group 3 (< half) |
4|9 5|478 6|228 7|1 8| 9| �10 Group 4 (> half) |
(A) Explore the data with a side-by-side boxplot. The boxplots are shown below. Because of the small ns it is hard to say anything other than group 1 and group 2 seem to have higher averages than groups 3 and 4. The three outside values warrant further scrutiny.
(B) Conduct an ANOVA.
(C) ...discuss your findings.
- Testing H0: �1 = �2 = �3 = �4 versus H1: at least one population mean differs
- Fstat = 4.15 w/ df1 = 3 and df2 = 21; P = 0.019.
- The difference is significant, confirming non-random differences among the groups.
- The descriptive statistics should be discussed in this context.