Use this description for Questions 1-4.

Dr. Voelz and his students are studying caddisfly larvae (Trichoptera) in the Mississippi River. Like many insects, caddisflies grow in a series of easily distinguishable stages (called instars), separated by a molt. He is interested in understanding the distribution of growth stages in three families of caddisflies. For each insect captured, he identifies its family (one of the three) and its instar (first, second, third).

1. If Dr. Voelz wants to know how many first instar larvae have been found, this question requires us to calculate a

a. Mean

b. Conditional probability

c. Count

d. Marginal value

2. The explanatory variable in Question 1 above was

a. Instar

b. Family of caddisfly

c. There are two response variables

d. There is really only one variable in the question

3. If Dr. Voelz wants to estimate how many of the third instar larvae in the population are in the family Hydropsychidae, this question requires us to calculate a

a. Mean

b. Conditional probability

c. Count

d. Marginal value

4. The explanatory variable in the question above is

a. Instar

b. Family of caddisfly

c. There are two response variables

d. There is really only one variable in the question

Use this description for Questions 5-8.

Dr. Fink is conducting a study on the safety of food in the local grocery store. He has collected 19 random samples of raw beef, and for each one he has tested it for occurrence of the bacteria Salmonella.

5. The individuals in this study are

a. Dr. Fink

b. The grocery store

c. Meat samples

d. Salmonella bacteria

6. To find out how many of the beef samples he collected have tested positive, he needs to calculate a

a. Mean

b. Count

c. Standard deviation

d. Conditional probability

7. To estimate how often beef samples in the store are infected, he needs to calculate a

a. Mean

b. Count

c. Proportion

d. Conditional probability

8. To estimate how often chicken samples in the store are infected, he needs to calculate a

a. Count

b. Frequency

c. Conditional probability

d. He needs to collect additional information

Use this description for Questions 9-15.

A team of veterinarians are trying to design dietary supplements for dogs that help to prevent premature birth of puppies. They begin an experiment with two different supplements and 14 pregnant female dogs at the same stage of pregnancy. The dogs are given supplements for four weeks, and at the end the vets record whether each dog had any premature births.

9. The individuals in this study are

a. The veterinarians

b. The puppies

c. The mother dogs

d. The dietary supplements

10. The veterinarians want to calculate how many mother dogs in the sample were given supplement 1 and then had a premature birth. To do this, they need to calculate a

a. Mean

b. Marginal value

c. Count

d. Conditional probability

11. The veterinarians want to estimate how many dogs in their larger practice would be given supplement 2 and then had a premature birth. To do this, they need to calculate a

a. Mean

b. Marginal value

c. Count

d. Conditional probability

12. In the previous question, the explanatory variable is

a. The puppies

b. The mother dogs

c. The dietary supplements

d. There is no explanatory variable 13. The veterinarians need to know how many mother dogs in the sample had premature births. To calculate this, they need a

a. Mean

b. Count

c. Marginal value

d. Conditional probability

14. In the previous question, the explanatory variable is

a. The puppies

b. The mother dogs

c. The dietary supplements

d. There is really only one variable in the question

15. The veterinarians want to know how many puppies were born per mother dog, following a regimen of dietary supplement 2. To do this, they need to calculate a

a. Mean

b. Marginal value

c. Count

d. Frequency

e. Conditional probability

Use this description for Questions 16-20.

The SCSU grounds crew is in charge (among other things) of keeping the grass on campus looking good. An ecology class is working with them to evaluate their success. We chose 48 square meters of turf in different locations on campus to monitor, and categorized the plots according to natural wear due to foot traffic (high, medium, low). Then we identified all plants in the plots, including both grass and weeds.

16. What are the individuals in this study?

a. The grounds crew

b. The grass

c. The weeds

d. The turf plots

e. The wear patterns (high, medium, low)

17. We want to know if high wear areas are more likely to have weeds than low wear areas. For this scientific question, the explanatory variable is

a. The 48 square meters

b. The grounds crew vs. the ecology students

c. The number of weed species

d. The wear patterns (high, medium, low)

18. The correct summary statistic to answer the above question is (we actually need two of them and compare to each other) a

a. Mean

b. Marginal value

c. Count

d. Frequency

e. Conditional probability

19. We now want to know if high wear areas have more weeds in them than low wear areas. For this scientific question, the response variable is

a. The 48 square meters