For each of the following questions, please identify the appropriate statistical technique to use to answer the scientific question posed. Use the same set of answers for every question. 1-sample z test for proportions 2-sample z test for proportions correlation analysis 1-sample t test 2-sample t test linear regression 1-variable chi-square test 2-variable chi-square test analysis of variance

1. A medical researcher is interested in cholesterol readings in humans, and their ability to predict risk of heart attacks. She measures the average HDL cholesterol readings in samples from 43 cities, and collects heart attack rates (# per thousand individuals) by making inquiries at hospitals in the same 43 cities.

2. The same medical researcher learns from the Center for Disease Control that the U.S. heart attack rate is 0.23% per individual per year. She now wants to know if the proportion of heart attack rate from her city is significantly different from the national figure.

3. Dragonflies were observed in a wetland preserve to investigate possible effects of body size on male dragonfly territorial ability. Eleven male dragonflies with territories were captured with nets and wing length measured, and territory quality was evaluated for each insect on a quantitative scale from 10 (high quality) to 1 (low).

4. The dragonfly researchers wanted to test the same scientific question, but in a slightly different way. They compared the average wing lengths of the 11 dragonflies from the first sample to the average wing lengths of another sample of 11 male dragonflies which were not observed to have territories. They are interested in knowing if there is a statistical difference between average wing lengths in the two samples.

5. While censusing weeds in eight pots, the number of leaves was counted on each plant. The researchers next want to know if there are significant differences in the average number of leaves per plant among all of the the eight pots.

6. Woodlice (a.k.a. pillbugs or roly-polies) often have gut parasites. We collect 4 woodlice specimens for three different species, dissect their digestive organs, and identify the total number of parasites. We want to know if any of the three species of woodlice have a significantly greater average number of parasites compared to the other woodlice species.

7. Climate change researchers are interested in the amount of carbon sequestered in different habitats and how this varies with temperature. Remote sensing equipment is used to estimate the annual carbon uptake in 30 identically sized plots in grassland, deciduous forest and deciduous forest (10 plots in each habitat). They compare the values from 2006 (a really warm year) and 1996 (a really cold year) in all the plots, and record whether they went up from 1996 to 2006, went down, or stayed about the same.

8. Samples of zooplankton were collected from 25 lakes to investigate whether greater than 50 percent of the lakes had invasive spiny water flea populations. We want to know if the proportion of our lake samples is significantly different than 50 percent for the invasive spiny water flea (Bythotrephes longimanus).

9. The wattle thickness (mm) of 15 randomly selected chickens was measured before and after a treatment with an enzyme. Chicken wattles were measured, the enzyme was administered, and then the wattles were re-measured two months later. We want to know if the enzyme has a significant effect on average wattle thickness.

10. Your local health department conducts a course on food handling. To evaluate this course, you select a SRS of restaurants from the list of licensed restaurants. For the restaurants, you search the list of violations found by the health department during the last two years as well as the list of restaurants with employees who have attended the course during the last two years. For each restaurant in your sample, you record a) whether their manager attended the food handling course and b) whether a violation was reported. You want to know if restaurants are statistically less likely to have violations if their manager has taken the course.