Question

An experiment was carried out to measure the effect of growth hormone on girls affected by a growth disorder called Turner’s syndrome. A total 68 girls participated in the study. Half of the girls were placed into the treatment group; these girls were given the active drug. The other half of girls were placed into the control group and were given a placebo with no active ingredients. Their heights were measured at the time the hormone was first administered and again one year later & their growth was determined.

a) What are the two variables of interest in this study? (Hint: one is categorical and one is quantitative)

b) Who is the population of interest? Be specific.

c) Who is the sample? Be specific.

d) Suppose we are told that the 68 girls in the study have an average height of 57 inches. Is the number 57 a statistic or a parameter? Explain.

2. A charitable nonprofit organization wants to test two methods of fundraising. A total of 1000 past donors are randomly selected from the organizations database. Half will be sent literature about the successful activities of the charity and asked to make another donation. The other 500 donors will be contacted by phone and asked to make another donation. For each person, whether or not they decided to donate again (Yes/No) is recoded.

a) What are the two variables of interest in this study?

b) Who is the population of interest? Be very specific.

3. Anna’s hummingbirds (a specific species) are among the most common hummingbirds along the Pacific Coast. It is known that for the population of all Anna’s hummingbirds, the average weight is 4.55 grams. Suppose that in a remote part of the Grand Canyon, a researcher catches, weighs, and releases a random sample of 15 of these birds and calculates an average weight of 4.29 grams. Use the information above to match each of the items to its correct term.

1. 4.29 grams A. Population

2. The 15 birds caught by the researcher B. Parameter

3. All Anna’s hummingbirds C. Sample

4. 4.55 grams D. Statistic

4. Classify each variable according to its data type (Quantitative OR Categorical)

Variable Name Q or C

Type of Cell Phone

Treatment Group (control vs active drug)

SAT Score

Airline Carrier

Grams of gluten

Pages in a book

Ethnicity

Favorite Band

5. Is insomnia related to education status? Researchers at the Universities of Memphis, Alabama at Birmingham, and Tennessee investigated this question in the Journal of Abnormal Psychology (Feb. 2005). Adults living in Tennessee were selected to participate in the study, which used a random-digit telephone dialing procedure. Two of the many variables measured for each of the 575 study participants were number of years of education and insomnia status (normal sleep or chronic insomniac). The researchers discovered that the fewer the years of education, the more likely the person was to have chronic insomnia.

a) Identify the population and the sample.

b) Identify the data collection method. Are there potential biases in the method used? Explain.

c) What data type are the two variables mentioned in the study description above?

d) What inference did the researchers make?

6. A manufacturer of table saw blades is interested in determining whether a narrower blade will cause less burning of wood when cutting very hard woods, such as maple. To answer this question, engineers obtain 20 similar one-inch-thick hard maple boards. Half (or 10) of the boards are sawed using the new, narrow-style blade, and the other half (or 10) of the boards are sawed using the standard-width blade. All cuts are done at the same feed rate (the rate at which the board is pushed against the blade to make the cut). The engineers then measure the amount of burning (rated on a scale of 1 to 10, with 10 being the worst) on each board.

What are the observations in this study?

7. Allan has a large jar of 10,000 pennies on his desk. Consider all the pennies in this jar to be a population. The mean age of this population of pennies is 25 years, and the oldest penny is from the year 1935. Allan takes a sample of 80 pennies from the jar and finds the mean age of the sample to be 12.5 years.

Which number is the statistic in this example? How do you know?

8. In Autumn 2017, total enrollment at the OSU Columbus campus was 59,837 students. A survey was conducted in which a simple random sample of 400 of these students was chosen and asked whether they would support eliminating classes on Fridays. A total of 62% of the 400 students surveyed answered "yes" to this question. We would call the number 62% a __________.

a) population.

b) sample.

c) statistic.

d) parameter.

e) census.

9. A recent article in the Wisconsin State Journal reported that the average US resident consumes 23.1 gallons of fluid milk each year. Suppose a researcher for the US Department of Agriculture conducts a study of 40 family-run dairy farms in the Midwest. They calculate the average amount of fluid milk consumed by the 142 individuals who live on the farms to be 30.2 gallons.

Use the information above to match each of the items to its correct term. You will not use every letter.

______ 1. Population

______ 2. Parameter

______ 3. Sample

______ 4. Statistic

A. 30.2 gallons

B. All US residents

C. 23.1 gallons

D. 142 individuals who live on dairy farms

E. 40 family-run dairy farms

F. Average US resident

10. Multiple Choice: clearly highlight or bold your answer

The telephone company studying residents of Los Angeles says (with certainty) that 62% of all residential phone numbers in Los Angeles are unlisted. A telephone survey contacts a random sample of 1000 Los Angeles telephones numbers, of which 58% are unlisted. In this setting,

a) 62% is a parameter and 58% is a statistic.

b) 58% is a parameter and 62% is a statistic.

c) 62% and 58% are both parameters.

d) 62% and 58% are both statistics.

e) There are no statistics in this example.

11. The following contingency table yields information on ? = 1620 drug related charges in MN. Two categorical variables were recorded about each charge. One variable is the type of offense (manufacturing, possession, sale), and the other is the type of drug involved (Amphetamines, cocaine, crack, marijuana, meth).

Drug Type of Offense Total Manufacture Possession Sale

Amphetamine 5 17 8 30

Cocaine 192 171 363

Crack 411

Marijuana 0 36 63

Meth 79 319 753

Total 84 786 750 1620

a) Using the row and column totals, fill in the missing cells of this table.

b) How many drug related charges were for possession of Cocaine?

c) According to these data, what is the second most prevalent drug type?

d) How many drug related charges were for possession of Meth?

e) Of the meth related charges, what percent were for possession?

f) What percent of Possess

Answer 1

Solution-!a;

One variable is Effect of Active ingredient

Other variable is growth

b) Who is the population of interest? Be specific.

girls affected by a growth disorder called Turner’s syndrome

c) Who is the sample? Be specific.

A total of 68 girls participated in the study is the sample

n=68

d) Suppose we are told that the 68 girls in the study have an average height of 57 inches. Is the number 57 a statistic or a parameter? Explain.

68 is sample and the statistics which describe sample is called statisitc

so average height of 57 inches

xbar =57 is a statistic