Unit 1 Section 1 Exercises

1. What are the objectives of statistics?
2. What is meant by a population in statistics?
3. What is a simple random sample?
4. How does a sample survey differ from an experimental study?
5. How does an observational study differ from an experimental study?
6. What is meant by keeping a "data trail"?
7. What are the six steps in processing data preliminary to statistical analysis?

It is suspected that pond farming of sturgeon in Florida could become a large industry due to the rapid growth, value of processed sturgeon eggs (caviar) as well as the excellent quality of the fish meat. The composition of the fish diet is critical to all of the above factors. A researcher wishes to estimate the growth rate over six months of sturgeon maintained on two different commercial fish foods. Forty sturgeon fingerlings are selected from a large nursery pond an and each is randomly assigned to one of the two diets, with twenty fish to each diet.

1. What is the population of interest here?
2. What characteristics of the population are of interest to the researcher?
3. What kind of sample was selected?
4. Where do you expect to find variability in responses?
5. A comparison is going to be made between the diets, what aspects of the effect of the diets on the population will be compared?

Sturgeon can grow to fairly large sizes, sizes typically larger than other freshwater fish (such as catfish or talipia) grown commercially in ponds. You have been asked to help a commercial sturgeon grower assess three commercial fish scaling devices for their use with sturgeon. Through each scaling machine you will pass 10 fish and at the end assess the completeness of scale removal.

1. What is the population of interest here?
2. What characteristics of the population are of interest to the researcher?
3. What kind of sample was selected?
4. Where do you expect to find variability in responses?
5. A comparison is going to be made between the scaling devices, what aspects of the effect of the processing will be compared?

Fish are at the top of the food chain and as such can be excellent bioaccumulators of contaminants. There is some concern that since sturgeon are bottom feeders, they may have higher exposure to contaminated bottom sediments and as such, eating commercially grown sturgeon might pose a health risk. The first step in a risk assessment is determining the level of contaminant in the fish meat. You select 3 fish from each of two ponds from each of 3 commercial growers (3 x 2 x 3 = 18 total fish). From each fish you select two samples of fish meat, one from the white (muscle) layer and one from the dark (fatty) layer. Each meat sample is then assessed for its level of contamination.

1. What is the population of interest here?
2. What characteristics of the population are of interest to the researcher?
3. What kind of sample was selected?
4. Where do you expect to find variability in responses?
5. A comparison is going to be made between the fish meat layers, what aspects will be compared?

Over one-hundred years ago, sturgeon meat could be found in most fish markets along the US Eastern seaboard. Overfishing reduced stocks to commercially unsustainable levels and sturgeon were no longer available at the market. Since Florida is thinking of investing in sturgeon fish production, it has been determined that a marketing survey is needed to assess potential consumer acceptance. Three eastern US cities of comparable size are chosen for the initial survey. In each city, five supermarkets are selected as test sites. On a prespecified day, shoppers at each selected supermarket are offered processed sturgeon meat to taste and asked to complete a short questionnaire about aspects of the meat.

1. What is the population of interest here?
2. What characteristics of the population are of interest to the researcher?
3. What kind of sample was selected?
4. Where do you expect to find variability in responses?
5. A comparison is going to be made between the cities, what aspects will be compared?