Question 1

When we say that the number is "statistically significant," which of these is closest to what we mean?

Accepted Answer

Statistical significance typically means that the observed difference or relationship in the data is unlikely to have occurred by chance alone, according to a predetermined threshold (usually a p-value). This suggests that the effect or difference is likely due to a specific cause or variable rather than random variation.

Question 2

In a prospective observational study, the members of the experimental group are exposed to the suspected causal agent by the investigators.

Accepted Answer

In a prospective observational study, the investigators observe and collect data without intervening or exposing subjects to any specific conditions or treatments.

Question 3

Evaluate the following analogical argument:
Hey, Coach! I know somebody good for our volleyball team. Her name is Stacy, and she hasn't played much volleyball, but she's a great basketball player.

Accepted Answer

The answer of Evaluate the following analogical argument:
Hey, Coach! I...

Question 4

When an experiment displays an outcome that is statistically significant at the .05 level, it means that

Accepted Answer

Statistical significance at the .05 level means there is a 5 percent chance (or less) that the observed results are due to random chance, implying a 95 percent confidence that the results are not due to chance.

Question 5

Evaluate the following analogical argument:
I like Fuji apples; I'll bet Fuji pears are good too.

Accepted Answer

The answer of Evaluate the following analogical argument:
I like Fuji...

Question 6

Johnson is hired by a company to see if a new product, Topocal, will cause hair to grow on the heads of bald men. He recruits one thousand bald men and randomly divides them into two groups: Five hundred men (group A) rub Topocal on their scalps each day; the other five hundred (group B) rub a standard skin lotion on their scalps each day. After two months, Johnson checks to see what the results have been. He finds that there has been hair growth in 7 percent of group A and in 2 percent of group B.What is the sample?

Accepted Answer

The sample refers to the specific group of individuals from the population who are actually participating in the study. In this case, the sample is the bald men who participated in the study, which includes both groups A and B.

Question 7

Evaluate the following analogical argument:
When Halley's comet appeared a few years ago, there was an upsurge in the number of suicides across the country. The same thing happened when the Hale-Bopp comet appeared in 1997. I'll bet the next appearance of a visible comet will produce a rash of suicides.

Accepted Answer

The answer of Evaluate the following analogical argument:
When Halley's comet...

Question 8

Evaluate the following analogical argument:
We have visited seven cities in southern Spain, and every one of them has a bull ring. I'll bet there's one in the next Spanish city we visit.

Accepted Answer

The answer of Evaluate the following analogical argument:
We have visited...

Question 9

The claim "Fouled spark plugs kept the car from starting" implies that the car would have started if the spark plugs had not been fouled.

Accepted Answer

The answer of The claim "Fouled spark plugs kept the...

Question 10

Rank the following analogical arguments:
a. Look, our stereo is a Panasonic and so is our TV, and we've never had any trouble with either of them. Let's get the Panasonic answering machine. Why take chances?
b. Look, our stereo is Japanese and so is our TV, and we've never had any trouble with either of them. Let's get the Japanese answering machine. Why take chances?
c. Look, Frank's answering machine is a Panasonic and so is Heather's, and they both say they've never had trouble with them. Let's get the Panasonic answering machine. Why take chances?

Accepted Answer

The answer of Rank the following analogical arguments:
a. Look, our...

Question 11

Johnson is hired by a company to see if a new product, Topocal, will cause hair to grow on the heads of bald men. He recruits one thousand bald men and randomly divides them into two groups: Five hundred men (group A) rub Topocal on their scalps each day; the other five hundred (group B) rub a standard skin lotion on their scalps each day. After two months, Johnson checks to see what the results have been. He finds that there has been hair growth in 7 percent of group A and in 2 percent of group B.The category that best fits this study is

Accepted Answer

This study is a randomized controlled experiment because participants were randomly assigned to either the treatment group (those using Topocal) or the control group (those using a standard skin lotion), and the outcomes were directly compared after a specific period.

Question 12

Johnson is hired by a company to see if a new product, Topocal, will cause hair to grow on the heads of bald men. He recruits one thousand bald men and randomly divides them into two groups: Five hundred men (group A) rub Topocal on their scalps each day; the other five hundred (group B) rub a standard skin lotion on their scalps each day. After two months, Johnson checks to see what the results have been. He finds that there has been hair growth in 7 percent of group A and in 2 percent of group B.What if Johnson had started with 2,000 bald men (1,000 in each group) and got the same 7 and 2 percent figures? Would this have made any difference for the significance of Johnson's results?

Accepted Answer

Doubling the sample size while maintaining the same percentage differences (7% for group A and 2% for group B) would not change the significance of the results. It would still indicate a difference between the two groups, potentially making the results more robust due to the larger sample size, but the statistical significance of the difference observed (5 percentage points difference) would remain significant.

Question 13

Johnson is hired by a company to see if a new product, Topocal, will cause hair to grow on the heads of bald men. He recruits one thousand bald men and randomly divides them into two groups: Five hundred men (group A) rub Topocal on their scalps each day; the other five hundred (group B) rub a standard skin lotion on their scalps each day. After two months, Johnson checks to see what the results have been. He finds that there has been hair growth in 7 percent of group A and in 2 percent of group B.What is the population?

Accepted Answer

The population refers to the entire group that the study is intended to apply to, which in this case is bald men in general.

Question 14

The claim "Fluoridated water prevents tooth decay," if , implies that fluoridated water would prevent tooth decay in the majority of individuals who use it.

Accepted Answer

The answer of The claim "Fluoridated water prevents tooth decay,"...

Question 15

Evaluate the following analogical argument:
The stock market has made huge gains during each of the past four years. I'm willing to put my money on the claim that it will do the same this coming year.

Accepted Answer

The answer of Evaluate the following analogical argument:
The stock market...

Question 16

In prospective observational studies, we use "d" to stand for

Accepted Answer

In prospective observational studies, "d" typically represents the difference in the frequency of an effect (outcome) between the experimental group and the control group.

Question 17

Johnson is hired by a company to see if a new product, Topocal, will cause hair to grow on the heads of bald men. He recruits one thousand bald men and randomly divides them into two groups: Five hundred men (group A) rub Topocal on their scalps each day; the other five hundred (group B) rub a standard skin lotion on their scalps each day. After two months, Johnson checks to see what the results have been. He finds that there has been hair growth in 7 percent of group A and in 2 percent of group B)Given the size of Johnson's two groups, would you say that the results of the test are statistically significant?

Accepted Answer

The difference in hair growth between the two groups (7% in group A vs. 2% in group B) suggests that Topocal may have an effect on hair growth. Given the sample size of 500 in each group, this difference is likely to be statistically significant, indicating that the observed effect is not due to chance.

Question 18

Evaluate the following analogical argument:
Can I recommend a good mechanic? Sure-B&M Tuneup. I've been taking my car there for years, and I've never had a single complaint. Of course, I have an old Chevy, and you drive a Mazda-one of those rotary-engine jobs, isn't it?

Accepted Answer

The answer of Evaluate the following analogical argument:
Can I recommend...

Question 19

In a retrospective observational study, none of the members of the control group show the effect of the cause being investigated.

Accepted Answer

In a retrospective observational study, the control group is used for comparison against the group exposed to the cause being investigated. It's possible for members of the control group to show the effect due to other factors, but typically at a lower rate than the exposed group if the cause has an effect.

Question 20

Evaluate the following analogical argument:
Prostitution is legal in the Netherlands, and it doesn't seem to produce any terrible societal problems. I'll bet it would be the same in the United States.

Accepted Answer

The answer of Evaluate the following analogical argument:
Prostitution is legal...

Quiz 11: Performance Evaluation Revisited: a Balanced Approach

When we say that the number is "statistically significant," which of these is closest to what we mean?

In a prospective observational study, the members of the experimental group are exposed to the suspected causal agent by the investigators.

Evaluate the following analogical argument: Hey, Coach! I know somebody good for our volleyball team. Her name is Stacy, and she hasn't played much volleyball, but she's a great basketball player.

When an experiment displays an outcome that is statistically significant at the .05 level, it means that

Evaluate the following analogical argument: I like Fuji apples; I'll bet Fuji pears are good too.

Evaluate the following analogical argument: We have visited seven cities in southern Spain, and every one of them has a bull ring. I'll bet there's one in the next Spanish city we visit.

The claim "Fouled spark plugs kept the car from starting" implies that the car would have started if the spark plugs had not been fouled.

The claim "Fluoridated water prevents tooth decay," if , implies that fluoridated water would prevent tooth decay in the majority of individuals who use it.

Evaluate the following analogical argument: The stock market has made huge gains during each of the past four years. I'm willing to put my money on the claim that it will do the same this coming year.

In prospective observational studies, we use "d" to stand for

Evaluate the following analogical argument: Can I recommend a good mechanic? Sure-B&M Tuneup. I've been taking my car there for years, and I've never had a single complaint. Of course, I have an old Chevy, and you drive a Mazda-one of those rotary-engine jobs, isn't it?

In a retrospective observational study, none of the members of the control group show the effect of the cause being investigated.

Evaluate the following analogical argument: Prostitution is legal in the Netherlands, and it doesn't seem to produce any terrible societal problems. I'll bet it would be the same in the United States.