What is the correlation coefficient for percent cigarette smokers and percent binge drinkers?
A. –0.1887
B. –0.0356
C. 0.0160
D. 0.0356
E. 0.1887
Marine biologists want to determine whether a small increase in the acidity of sea water would
adversely affect marine life. They randomly assigned several Entacmaea quadricolor , one species
of sea anemone, to one of eight aquariums that had been prepared with environments as similar as
possible to the natural habitat. Then they randomly selected four tanks, and gradually increased the
acidity of the water. They monitored the health of the anemones for the duration of the study. Which
of these statements is NOT true about this study?
A. An advantage of using only one variety of sea anemones is that there should be less variability
in the response to each treatment.
B. A disadvantage of using only one variety of sea anemones is that the scope of inference is
limited only to that type of anemone.
C. An advantage of using aquariums is that it is easier to maintain control to avoid confounding
factors.
D. A disadvantage of using aquariums is that the anemones might respond differently in the ocean
than they do in aquariums.
E. If the anemones in the aquariums with increased acidity are less healthy than those without
increased acidity, it cannot be determined that the increased acidity caused the response.
- In a large high school, the student council wants to select a sample to survey the student body. They
will first select 25 freshmen, then select 25 sophomores, then 25 juniors, and then finally 25
seniors. This is an example of a
A. Cluster sample
B. Stratified sample
C. Simple random sample
D. Convenience sample
E. Systematic sample