Exercises

1.Explain the difference between an observational and an experimental study.

2.Name and define the three types of observational studies.

3.List some advantages and disadvantages of an observational study.

4.List some advantages and disadvantages of an experimental study. Page 3 of 9

5.What is the difference between an experimental study and a quasi-experimental study?

6.What is the difference between independent variables and dependent variables?

7.Why are a treatment group and a control group used in a statistical study?

8.Explain the Hawthorne effect.

9.What is a confounding variable?

10.Define the placebo effect in a statistical study.

11.What is meant by blinding and double-blinding?

12.Why do researchers use randomization in statistical studies?

13.What is the difference between a completely randomized design and a matched-pair design?

14.Why is replication used in statistical studies?

For Exercises 15-18, determine whether an observational study or an experimental study was used.

15.A survey was taken to see how many times in a month a person encountered a panhandler on the street.

16.A study using college students was conducted to see if the percentage of males who pay for a date was equal to the percentage of females who pay for a date.

17.A study was done on two groups of overweight individuals. Group 1 was placed on a healthy, moderate diet. Group 2 was not given any diet instructions. After 1 month, the members were asked how many times they engaged in binge eating. The results of the two groups were compared. 18.Two groups of students were randomly selected. The students in Group 1 were enrolled in the general studies program. Group 2 students were enrolled in a specific major program (i.e., business, engineering, social work, criminal justice, etc.). At the end of the first year of study, the grade point averages of the two groups were compared.

In Exercises 19-22, identify the independent variable and the dependent variable.

19.According to the British Journal of Sports Medicine, a regular 30-minute workout could slash your risk of catching a cold by 43%.

20.The Journal of Behavioral Medicine reported that sharing a hug and holding hands can limit the physical effects of stress such as soaring heart rate and elevated blood pressure.

21.A study was conducted to determine whether when a restaurant server drew a happy face on the check, that would increase the amount of the tip.

22.A study was conducted to determine if the marital status of an individual had any effect on the cause of death of the individual.

25 For Exercises 23-26, suggest some confounding variables that the researcher might want to consider when doing a study.

23.Psychology Today magazine reports that the more intelligent a person is (based on IQ), the more willing the person is to make a cooperative choice rather than a selfish one.

24.The New England Journal of Medicine reported that when poor women move to better neighborhoods, they lower the risk of developing obesity and diabetes.

25.A leading journal reported that people who have a more flexible work schedule are more satisfied with their jobs.

26.York University in Toronto, Canada, stated that people who had suffered from fibromyalgia were able to reduce their pain by participating in twice-weekly yoga sessions.

For Exercises 27-31, give a reason why the statement made might be misleading.

27.Our product will give you the perfect body.

28.Here is the whole truth about back pain.

29.Our pain medicine will give you 24 hours of pain relief.

30.By reading this book, you will increase your IQ by 20 points.

31.Eating 21 grams of fiber may help you to lose weight.

32.List the steps you should perform when conducting a statistical study.

33.Beneficial Bacteria According to a pilot study of 20 people conducted at the University of Minnesota, daily doses of a compound called arabinogalactan over a period of 6 months resulted in a significant increase in the beneficial lactobacillus species of bacteria. Why can't it be concluded that the compound is beneficial for the majority of people?

34.Comment on the following statement, taken from a magazine advertisement: "In a recent clinical study, Brand ABC (actual brand will not be named) was proved to be 1950% better than creatine!"

35.In an ad for women, the following statement was made: "For every 100 women, 91 have taken the road less traveled." Comment on this statement.

36.In many ads for weight loss products, under the product claims and in small print, the following statement is made: "These results are not typical." What does this say about the product being advertised?

37.In an ad for moisturizing lotion, the following claim is made: ". . . it's the number 1 dermatologist-recommended brand." What is misleading about this claim?

38.An ad for an exercise product stated: "Using this product will burn 74% more calories." What is misleading about this statement?

39."Vitamin E is a proven antioxidant and may help in fighting cancer and heart disease." Is there anything ambiguous about this claim?

Explain.

40."Just 1 capsule of Brand X can provide 24 hours of acid control." (Actual brand will not be named.) What needs to be more clearly defined in this statement?

41.". . . Male children born to women who smoke during pregnancy run a risk of violent and criminal behavior that lasts well into adulthood." Can we infer that smoking during pregnancy is responsible for criminal behavior in people?

42.Caffeine and Health In the 1980s, a study linked coffee to a higher risk of heart disease and pancreatic cancer. In the early 1990s, studies showed that drinking coffee posed minimal health threats. However, in 1994, a study showed that pregnant women who drank 3 or more cups of tea daily may be at risk for miscarriage. In 1998, a study claimed that women who drank more than a half-cup of caffeinated tea every day may actually increase their fertility. In 1998, a study showed that over a lifetime, a few extra cups of coffee a day can raise blood pressure, heart rate, and stress (Source: "Bottom Line: Is It Good for You? Or Bad?" by Monika Guttman, USA TODAY Weekend). Suggest some reasons why these studies appear to be conflicting.

For Exercises 1-8, state whether descriptive or inferential statistics has been used.

1.By 2040 at least 3.5 billion people will run short of water (World Future Society).

2.In a sample of 100 individuals, 36% think that watching television is the best way to spend an evening.

3.In a survey of 1000 adults, 34% said that they posted notes on social media websites (Source: AARP Survey).

4.In a poll of 3036 adults, 32% said that they got a flu shot at a retail clinic (Source: Harris Interactive Poll).

5.Allergy therapy makes bees go away (Source: Prevention).

6.Drinking decaffeinated coffee can raise cholesterol levels by 7% (Source: American Heart Association).

7.In a survey of 1500 people who gave up driving, the average of the ages at which they quit driving was 85. (Men's Health)

8.Experts say that mortgage rates may soon hit bottom (Source: USA TODAY).

For Exercises 9-18, classify each as nominal-level, ordinal-level, interval-level, or ratio-level measurement.

9.Pages in the 25 best-selling mystery novels.

10.Rankings of golfers in a tournament.

11.Temperatures of 10 toasters.

12.Weights of selected cell phones.

13.Salaries of the coaches in the NFL.

14.Times required to complete a 6-mile bike ride.

15.Ratings of textbooks (poor, fair, good, excellent).

16.Number of amps delivered by battery chargers.

17.Ages of the players on a professional football team. Ratio

18.Categories of magazines in a physician's office (sports, women's, health, men's, news).

For Exercises 19-26, classify each variable as qualitative or quantitative.

19.Marital status of nurses in a hospital.

20.Time it takes 10 people to complete a New York Times crossword puzzle.

21.Weights of lobsters in a tank in a restaurant.

22.Colors of automobiles in a shopping center parking lot.

23.Amount of garbage (in pounds) discarded by residents of a high-rise apartment complex.

24.Capacity of the NFL football stadiums.

25.Ages of people living in a personal care home. Quantitative

26.The different species of fish sold by a pet shop store.

Qualitative For Exercises 27-34, classify each variable as discrete or continuous.

27.Number of street corner mailboxes in the city of Philadelphia.

28.Relative humidity levels in operating rooms at local hospitals.

29.Number of bananas in a bunch at several local supermarkets.

30.Ages of women when they were first married.

31.Weights of the backpacks of first-graders on a school bus.

32.Number of students each day who make appointments with a math tutor at a local college.

33.Duration of marriages in America (in years).

34.Ages of children in a preschool.

For Exercises 35-38, give the boundaries of each value.

35. 56 yards.

36. 105.4 miles.

37. 72.6 tons.

38. 9.54 millimeters.

For Exercises 39-44, classify each sample as random, systematic, stratified, cluster, or other.

39.In a large school district, all teachers from two buildings are interviewed to determine whether they believe the students have less homework to do now than in previous years.

40.All fast-food workers at a randomly selected fast-food restaurant are selected and asked how many hours per week they work.

41.A group of unmarried men are selected using random numbers and asked how long it has been since their last date.

42.Every 100th hamburger manufactured is checked to determine its fat content.

43.Mail carriers of a large city are divided into four groups according to gender (male or female) and according to whether they walk or ride on their routes. Then 10 are selected from each group and interviewed to determine whether they have been bitten by a dog in the last year. Stratified 44.People are asked to phone in their response to a survey question.

For Exercises 45-48, identify each study as being either observational or experimental.

45.Subjects were randomly assigned to two groups, and one group was given an herb and the other group a placebo. After 6 months, the numbers of respiratory tract infections each group had were compared.

46.A researcher stood at a busy intersection to see if the color of the automobile that a person drives is related to running red lights.

47.A sample of females were asked if their supervisors (bosses) at work were to hug them, would they consider that a form of sexual harassment? 48.Three groups of gamblers were randomly selected. The first group was given $25 in casino money. The second group was given a $25 coupon for food. The third group was given nothing. After a trip to the casino, each group was surveyed and asked their opinion of their casino experience.

For Exercises 49-52, identify the independent and dependent variables for each study.

49.A study was conducted to determine if crocodiles raised in captivity (i.e., in a zoo) grew faster than crocodiles living in the wild. Identify the explanatory variable and the outcome variable.

50.People who walk at least 3 miles a day are randomly selected, and their blood triglyceride levels are measured in order to determine if the number of miles that they walk has any influence on these levels.

51.In an article in the British Journal of Nutrition, two types of mice were randomly selected. One group received a thyme supplement for a specific time, while another group was used as a control group and received no supplements. The brains of the mice were then analyzed, and it was found that the brains of the group of mice that received the thyme supplements had antioxidant levels similar to those of younger mice. It was concluded that the thyme supplement increased the antioxidants in the brains of the mice.

52.A study was conducted to determine if workers who had a flexible work schedule had greater job satisfaction than those workers who worked a regular nine-to-fivework schedule. Dependent variablejob satisfaction.

For Exercises 53-58, explain why the claims of these studies might be suspect.

53.Based on a recent telephone survey, 72% of those contacted shop online.

54.In High Point County there are 672 raccoons.

55.A survey of a group of people said the thing they dislike most about winter is snow.

56.Only 5% of men surveyed said that they liked "chick flicks."

57.A recent study shows that high school dropouts spend less time on the Internet than those who graduated; therefore, the Internet raises your IQ.

58.Most shark attacks occur in ocean water that is 3 feet deep; therefore, it is safer to swim in deep water.

Determine whether each statement is true or false. If the statement is false, explain why.

1.Probability is used as a basis for inferential statistics.

2.When the sample does not represent the population, it is called a biased sample.

3.The difference between a sampling measure and a population measure is called a non-sampling error.

4.When the population of college professors is divided into groups according to their rank (instructor, assistant professor, etc.) and then several are selected from each group to make up a sample, the sample is called a cluster sample.

5.The variable temperature is an example of a quantitative variable.

6.The height of basketball players is considered a continuous variable.

7.The boundary of a value such as 6 inches would be 5.9-6.1 inches.

Select the best answer.

8.The number of ads on a one-hour television show is what type of data?

a.Nominal b.Qualitative c.Discrete d.Continuous

9.What are the boundaries of 25.6 ounces?

a .25-26 ounces b. 25.55-25.65 ounces c. 25.5-25.7 ounces d. 20-39 ounces

10.A researcher divided subjects into two groups according to gender and then selected members from each group for her sample. What sampling method was the researcher using?

a.Cluster b.Random c.Systematic d.Stratified

11.Data that can be classified according to color are measured on what scale?

a.Nominal b.Ratio c.Ordinal d.Interval

12.A study that involves no researcher intervention is called

a.An experimental study. b.A noninvolvement study. c.An observational study. d.A quasi-experimental study.

13.A variable that interferes with other variables in the study is called

a.A confounding variable. b.An explanatory variable. c.An outcome variable. d.An interfering variable.

Use the best answer to complete these statements.

14.Two major branches of statistics are _______ and _______.

15.Two uses of probability are _______ and _______

16.The group of all subjects under study is called a(n) _______.

17.A group of subjects selected from the group of all subjects under study is called a(n) _______.

18.Three reasons why samples are used in statistics: a._______ b._______ c._______

19.The four basic sampling methods are a._______ b._______ c._______ d._______

20.A study that uses intact groups when it is not possible to randomly assign participants to the groups is called a(n) _________________

21.In a research study, participants should be assigned to groups using ________ methods, if possible.

22.For each statement, decide whether descriptive or inferential statistics is used.

a.The average life expectancy in New Zealand is 78.49 years (Source: World Factbook).

b.A diet high in fruits and vegetables will lower blood pressure (Source: Institute of Medicine).

c.The total amount of estimated losses for Hurricane Katrina was $125 billion (Source: The World Almanac and Book of Facts).

d.Researchers stated that the shape of a person's ears is relative to the person's aggression (Source: American Journal of Human Biology). 37

e.In 2050, it is estimated that there will be 18 million Americans who are age 85 and over (Source: U.S. Census Bureau).

23.Classify each as nominal-level, ordinal-level, interval-level, or ratio-level of measurement.

a.Rating of movies as G, PG, and R

b.Number of candy bars sold on a fund drive

c.Classification of automobiles as subcompact, compact, standard, and luxury

d.Temperatures of hair dryers

e.Weights of suitcases on a commercial airliner

24.Classify each variable as discrete or continuous.

a.Ages of people working in a large factory

b.Number of cups of coffee served at a restaurant

c.The amount of drug injected into a guinea pig

d.The time it takes a student to drive to school

e.The number of gallons of milk sold each day at a grocery store

25.Give the boundaries of each.

a.32 minutes

b.0.48 millimeter

c.6.2 inches

d.19 pounds

e.12.1 quarts