CHAPTER 1 Test Your Knowledge

Driving Question 1

By answering the questions below and studying Infographics 1.2, 1.3, 1.4, and 1.7, you should be able to generate an answer for the broader Driving Question above.

KNOW IT

When scientists carry out an experiment, they are testing a ___________.

a. theory

b. question

c. hypothesis

d. control

e. variable

Of the following, which is the earliest step in the scientific process?

a. generating a hypothesis

b. analyzing data

c. conducting an experiment

d. drawing a conclusion

e. asking a question about an observation

In a controlled experiment, which group receives the placebo?

a. the experimental group

b. the control group

c. the scientist group

d. the independent group

e. all groups

In the studies of coffee and memory discussed, the independent variable is _____________ and the dependent variable is _____________.

a. caffeinated coffee; decaffeinated coffee

b. memory; caffeinated coffee

c. caffeine; memory

d. memory; caffeine

e. decaffeinated coffee; caffeinated coffee

Can an epidemiologist who finds a correlation between the use of tanning beds and melanoma (an aggressive form of skin cancer) in college-age women conclude that tanning beds cause skin cancer?

a. yes, as long as the correlation was statistically significant

b. yes, but only for college-age women

c. yes, but only melanoma skin cancer, not other forms of skin cancer

d. no; the study would have to be done with a wider range of participants (males and females of different ages) before it can be concluded that tanning beds cause melanoma

e. no; correlation is not proof of causation

USE IT

You carry out a clinical trial to test whether a new drug relieves the symptoms of arthritis better than a placebo. You have four groups of participants, all of whom have mildly painful arthritis (rated 7 on a scale of 1 to 10). Each group receives a daily pill as follows: control (group 1) - placebo; group 2- 15 mg; group 3- 25 mg; group 4- 50 mg. At the end of 2 weeks, participants in each group are asked to rate their pain on a scale of 1 to 10. What is the independent variable in this experiment? a. the amount of pain experienced at the start of the experiment

b. the amount of pain experienced at the end of the experiment

c. the degree to which pain symptoms changed between the start and the end of the experiment

d. the drug

e. The independent variable could be a, b, or c.

You are working on an experiment to test the effect of a specific drug on reducing the risk of breast cancer in postmenopausal women. Describe your control and experimental groups with respect to age, gender, and breast cancer status.

Design a randomized clinical trial to test the effects of caffeinated coffee on brain activity. Design your study so that the results will apply to as many people in as many scenarios as possible.

Driving Question 2

By answering the questions below and studying Infographics 1.3 and 1.4, you should be able to generate an answer for the broader Driving Question above.

KNOW IT

In which of the following would you have the most confidence?

a. a randomized clinical trial with 15,000 subjects

b. a randomized clinical trial with 5,000 subjects

c. an epidemiological study with 15,000 subjects

d. an endorsement of a product by a movie star

e. a report on a study presented by a news organization

What is the importance of statistical analyses?

a. They can reveal whether or not the data have been fabricated.

b. They can be used to support or reject the hypothesis.

c. They can be used to determine whether any observed differences between two groups are real or a result of chance.

d. all of the above

e. b and c

USE IT

You carry out a clinical trial to test whether a new drug relieves the symptoms of arthritis better than a placebo. You have four groups of participants, all of whom have mildly painful arthritis (rated 7 on a scale of 1 to 10). Each group receives a daily pill as follows: control (group 1) - placebo; group 2- 15 mg; group 3- 25 mg; group 4- 50 mg. At the end of 2 weeks, participants in each group are asked to rate their pain on a scale of 1 to 10. The mean pain rating of the participants was 6.5 for the placebo, 6.0 for 15 mg of the drug, 4.5 for 25 mg of the drug, and 4.5 for 50 mg of the drug. What is your next step?

a. Invest in the drug company.

b. Conclude that the drug relieves arthritis pain.

c. Run a statistical analysis to determine if the differences are significant.

d. Conclude that the drug doesn’t work very well (even the placebo group went down on the pain scale, and there was no difference in results between doses of 25 mg and 50 mg of the drug).

e. a and b

Looking at Infographic 1.4 (Sample Size Matters), you see that both graphs show a positive impact of caffeine on memory. However, the data in the graph on the right carry more weight. Why is that? If you read a study that reported only the data in the left graph, would you find the relationship to be compelling? Why or why not?

From what you have read in this chapter, would you say a 21-year-old Caucasian female can count on caffeinated coffee to reduce her risk of Parkinson disease?

a. yes, because the results of a peer-reviewed study showed that drinking caffeinated beverages reduced the risk of Parkinson disease

b. no, because participants in that peer-reviewed study were Japanese-American males; it cannot be inferred that the same results would hold for Caucasian females

c. no; she would have to restrict her consumption of coffee to decaffeinated coffee to reduce her risk of Parkinson disease

d. yes; coffee is known to reverse the symptoms of Parkinson disease

e. There are no data on the relationship between drinking caffeinated beverages and Parkinson disease because it would be unethical to conduct such an epidemiological study.

INTERPRETING DATA

Most statistical tests report a p value that determines whether or not the results are statistically significant (i.e., not produced by chance). Usually the cutoff for p values is 0.05: if the p value is less than 0.05 the results are considered to be statistically significant. The graph below shows data from a 2012 study published in the New England Journal of Medicine. The study examined the impact of the drug Tofacitinib on ulcerative colitis. From the data shown, what dose(s) of Tofacitinib is/are significantly better than the placebo in treating ulcerative colitis?

a. 0.5 mg

b. 3 mg

c. 10 mg

d. 15 mg

e. both 10 mg and 15 mg

f. All doses are more effective than the placebo.

SOURCE: Sandborn, W.J., et al. (2012) Tofacitinib, an oral Janus kinase inhibitor, in active ulcerative colitis. New England Journal of Medicine 367:616–624.

Driving Question 3

By answering the questions below and studying Infographics 1.2, 1.3, 1.4, 1.7, and 1.8, you should be able to generate an answer for the broader Driving Question above.

KNOW IT

You hear a news report about a new asthma treatment. What would you want to know before you asked your doctor if this treatment was right for you?

a. Was the drug tested in a randomized clinical trial?

b. How many participants were in the trial?

c. Was there a significant difference between the effect of the new drug and the treatment used in the control group?

d. Did any of the researchers have financial ties to the manufacturer of the new asthma drug?

e. all of the above

You are listening to a news report that claims a new study has found convincing evidence that a particular weight-loss product is much more effective than diet and exercise. What can you infer about “convincing” evidence in this case?

a. that it agrees with the hypothesis

b. that statistical tests showed significantly more weight loss in the participants who used the weight-loss product than those who relied on diet and exercise

c. that all the participants lost at least 10 pounds

d. that only the participants who used the weight-loss product lost weight

e. that the participants who used the weight-loss product lost an average of 3 pounds, while the participants that used diet and exercise lost an average of 2 pounds

USE IT

How can two different studies investigating the same thing (e.g., the relationship, if any, between caffeinated coffee and memory) come to different conclusions?

a. They may have had different sample sizes.

b. They may have used different types of participants (e.g., participants of different ages or professions).

c. They may have used different amounts of caffeine.

d. They may have evaluated memory differently (e.g., long-term vs. short-term memory).

e. all of the above

A scientist who reads an article in a scientific or medical journal can be confident that the report has been peer reviewed.

a. What is a “peer-reviewed” report? Is an article in a daily newspaper a peer-reviewed article?

b. What is the role of a peer reviewer of a scientific article?

c. Why do scientists place so much value on the peer-review process?

The mother of a friend is a self-described “coffee addict.” She recently received a diagnosis of Parkinson disease. Does her experience negate the results of the JAMA study described in this chapter? Why or why not?

You may have seen advertisements on television that show beautiful people with clear skin who claim that a specific skin care product is “scientifically proven” to reduce acne. The product reportedly gave these people glowing, clear skin.

a. Is their testimony alone strong enough evidence for you to act on? Why or why not?

b. What kind of scientific evidence would persuade you to spend money on this product? Explain your answer.

Driving Question 4

By answering the questions below and studying Infographics 1.2 and 1.3, you should be able to generate an answer for the broader Driving Question above.

USE IT

Following the prompts below, design a clinical trial to test the impact of a particular intervention on a specific aspect of human health. You will need to use everything you have learned to do this.

a. From scientific articles or press releases from health organizations you have read, or from your own experiences, what observation(s) can you start with?

b. Do some investigation to generate a testable hypothesis.

c. Design the trial. Consider sample size, whether or not you will use a placebo, what level of blinding you will use, and possible independent and dependent variables.