15. The are robust to outliers, whereas the are not.

Group of answer choices

mean and standard deviation; median and interquartile range

median and interquartile range; mean and standard deviation

median and standard deviation; mean and interquartile range

mean and median; standard deviation and interquartile range

standard deviation and interquartile range; mean and median

16. A study was conducted to assess the performance of outpatient substance abuse treatment centers. Three different types of units were evaluated: private for-profit, private not-for-profit, and public. Among the performance measures considered were minutes of individual therapy per session. Samples were selected from each type of treatment center and summary statistics are shown below, along with the ANOVA test performed by R: What are the appropriate null and alternative hypotheses for this test?

Group: N Mean Standard Deviation

Private For-Profit (FP) 37 47.90 14.66

Private Not-for-Profit (NFP) 312 55.53 11.68

Public 169 54.07 11.87

> anova_results <- aov(Minutes~Group,data=mins)

> summary(anova_results)

Df Sum Sq Mean Sq F value Pr(>F)

Group 2 1973 986.4 6.882 0.00112 **

Residuals 515 73814 143.3

Group of answer choices

a. H₀: all means are equal vs. H_a: all means are different

b. H₀: all means are equal vs. H_a: not all means are equal

c. H₀: all means are equal vs. H_a: at least two means are the same