CPS questions for Correlations and Controls lectures:

You observe that, over the past 4 decades, STD rates have declined after increases in beer taxes.

One proposal is that higher beer taxes cause reduced STD rates. Thus, increasing taxes will cause the STD rate to go down.

Which of the following models instead invoke a third variable to explain the cause of this correlation?

Causal model	Third variable?
Increased alcohol consumption increases promiscuity, which in turn increases STD rates. Higher beer taxes cause reduced promiscuity	(A)
Good economic times encourage politicians to raise taxes; good economic times also cause people to be more promiscuous; more promiscuity leads to higher STD rates	(B)
conservative governments tend to raise ‘sin’ taxes more than liberal governments; conservative governments also cause people to behave more promiscuously; more promiscuity leads to higher STD rates	(C)
beer tax revenue is used to provide cheap health care, and the availability of health care cures more STDs	(D)

Causal model	Cause	will STD rate go down if taxes raised?	Third variable?
Increased alcohol consumption increases promiscuity, which in turn increases STD rates. Higher beer taxes cause reduced promiscuity	tax rate	yes	no
Good economic times encourage politicians to raise taxes; good economic times also cause people to be more promiscuous; more promiscuity leads to higher STD rates	economy	no	yes
conservative governments tend to raise ‘sin’ taxes more than liberal governments; conservative governments also cause people to behave more promiscuously; more promiscuity leads to higher STD rates	gov’t	no	yes
beer tax revenue is used to provide cheap health care, and the availability of health care cures more STDs	tax rate	yes	no

		type of car
		sports	“safe”
Car color	red	accident rate high	(2)
	other	(1)	accident rate low

The correlation is observed that red cars have higher accident rates than other colors of cars. What combination of accident rates for cells (1) and (2) apply if car type instead of color is the cause of accident rate?

A) 1 high, 2 high

B) 1 high, 2 low

C) 1 low, 2 high

D) 1 low, 2 low

The test shown in the FC video was an experiment because

A) it included controls

B) it included replication

C) it manipulated the normal FC environment

D) all of the above

What is the most critical design feature of this experiment? Other features may be (very) desirable, but if this one is absent, the experiment could not possibly test whether the child can communicate information independently of the Facilitator?

A) randomization

B) replication

C) blind

D) standards

E) controls

Why was the study an experiment?

A) it included blind, replication, controls

B) the outcome was not what the Facilitators expected

C) there was a deliberate change in the usual way FC operated

D) because the children did not know the right answer

Which design features were shown to be part of these experiments?

A) randomization

B) replication

C) blind

D) controls

Which of the following studies describe experiments, regardless of whether the experiment was designed well or poorly. Some of these studies would be considered unethical, but the question is merely about which studies are experiments? (none, one, many)

(A) To test whether smoking causes lung cancer, you interview people about their smoking habits. You then identify two groups of individuals to observe for a period of two years: smokers and non-smokers. Yet during your observation period, some of the smokers have quit because they do not like the habit. At the end, your study has three groups: smokers who did not quit, smokers who quit, and those who never smoked. You then look for an association between lung cancer and level of smoking.

(B) You decide to rearrange your living room. You begin by moving the couch to a new location to see if you like it better in the new place or the old place.

(D) In 1918, astronomers awaited the solar eclipse to measure the distance of a star from the edge of the sun. This study was the first critical test of Einstein's general theory of relativity.

(E) A study is done to determine whether alcohol increases the incidence of birth defects. The study design involves giving 50 pregnant mice drinking water with 5% alcohol. The control group is 50 pregnant mice with no alcohol in their water. The study finds that those receiving alcohol had a slightly higher incidence of birth defects than those who did not.

(F) A researcher merely records the diets of a large number of pregnant women. He finds that women who took twice the recommended daily dose of vitamin A have a 1 in 57 chance of a child with birth defects.

Causal model

Third variable?

Causal model

Cause

will STD rate go down if taxes raised?

Third variable?

Car color

C) blind