Exam 1, Biology 301C, 14 September 1998

Language of evaluation

1-4) (2 pts each) We wish to test the model that players or teams with red sports uniforms have higher winning rates than players/teams wearing other colors of uniforms. For the following possible data, which consequences (A-D) apply? Note that this question is not about causation versus correlation, only about data and a model that happens to describe a correlation. Answer each question independently of the others. At least one answer, but possibly more (MTF). Ignore the possibility of sampling error.

A) The data are inconsistent with the model

B) The data are consistent with the model

C) The data support the model

D) The data are irrelevant to the model

E) None

1) Data: Winning rates by color in 100 olympic contests:

white = 13%, blue = 6% gold = 7% green = 4%, red = 8%, all others less than 3% each

A B C D E

2) Data: Winning rates by color in 100 high school football championships:

white = 5%, blue = 6% gold = 7% green = 4%, red = 9%, all others less than 3% each

A B C D E

3) Data: 18% of basketball teams wear red; 15% of football teams wear red. A B C D E

4) Data: Winning rates of blue uniforms are 51% A B C D E

5) (7 pts) The following points pertain to the book and lecture on evaluation. Which statements are true? MTF

(A) Classifying data as irrelevant to a model means that the data were not gathered according to the Ideal Data template.

(B) To “accept” a model means that it cannot be refuted in further tests.

(C) The criteria for acceptance of a model are rigid in science and society, and there is little legitimate room for disagreement as to whether a model should be accepted or not.

(D) A company wishing to obtain FDA approval to market a new drug must first show it is safe. This procedure thus uses the null model that the drug is harmful until proven safe. In contrast, for marketing an herbal remedy, there is no null model.

(E) In science and in many aspects of society, our willingness to reject a null model increases as evidence accumulates against that model. For example, in class, our acceptance of the safety of a vaccine (against the null model that the vaccine was not safe) increased as the sample of successful trials increased.

(F) A null model is part of every properly designed study. If the study does not have a null model, then it is not properly designed.

Correlations

6. (5pts) Which of the following statements describe a (non-zero) correlation? Do not choose any option that describes a zero correlation or for which a correlation is undefined. If insufficient information is given to determine whether a correlation exists, treat it as if there is no correlation. MTF

(A) Memory loss increases with age.

(B) As X increases, Y decreases

(D) Some women have long hair, some women have short hair.

(E) The average score on exam 2 was lower than the average on exam 1

(F) UT students are just as likely to party on Friday night as on Saturday night

7. (3 pts) MTF In class, “third variable” models, were used to

(A) Offer a way of explaining why correlations are consistent with many causal models

(B) Explain how X and Y can be correlated when they are not causally related.

8. (5 points) Which of the following constitutes an example of inferring causation from correlation (i.e., in which a correlation leads someone to infer the causal basis of the correlation)? Base your answer only on the information provided. Do not circle answers that merely describe a correlation or which infer correlation from causation. MTF

(A) Geneticists found that a certain gene (leptin) is defective in obese (fat) mice but not in normal mice. The biotech company Genentech bought the rights to this gene so that they could market human leptin as a diet drug that people would eat to lose weight.

(B) A person is more apt to make mistakes when they are sleepy than when they have had adequate sleep because the lack of sleep impairs judgment. As a consequence, sleepy drivers are involved in auto accidents more often than are awake drivers.

(C) Drivers talking on cell phones have higher accident rates than drivers not talking on cell phones. Consequently, several countries around the world have made it illegal to talk on cell phones while driving.

(D) You read that smokers have more health problems than non-smokers. You have never been a smoker, but this information and your desire to remain healthy increases your resolve to never smoke.

9. (4pts) Key code, name, and pad number. Fill in (AB) on scantron field 9 to indicate your key for this version of the exam. Be sure your name and pad number are correctly bubbled in on the scantron and that your name is on this exam form. If your name is not on this copy as well as the scantron form, you can be penalized 40 points, if we can even determine that you took the test.

10. (5 points) Mark all models(s) that are consistent with the information in the following graph. (That is, mark an answer if it cannot be ruled out using the information in the following graph.) Assume you have no data other than what is presented in this graph. MTF

(A) Increasing alcohol consumption might cause a decline in GPA.

(B) Alcohol consumption is positively correlated with GPA.

(D) Alcohol consumption is correlated with GPA.

(E) Alcohol consumption does not cause changes in GPA.

(F) Alcohol consumption does cause changes in GPA.

(G) After receiving mid-term results, students with poor scores increase their alcohol intake.

11. (5 pts) Consider the correlation that regions of cities with more lead in the water also have higher crime rates. Which of the following causal models of this correlation use a “third variable” to explain the correlation? MTF

Causal model	Cause invoke a third variable?
higher lead comes from old pipes in need of repair. Old pipes are more often found in the poorer parts of cities; poverty is what leads to higher crime.	Fill in (A) if a 3^rd variable is invoked
higher lead comes from old pipes in need of repair. Lead adversely affects behavior, causing more crime	Fill in (B) if a 3^rd variable is invoked
Lead in the diet changes a person’s hormone levels, and hormone levels in turn cause bad behavior/crime.	Fill in (C) if a 3^rd variable is invoked
higher lead comes from old pipes in need of repair. Old pipes also have more bacteria and other agents of disease; the higher disease agents lead to higher crime.	Fill in (D) if a 3^rd variable is invoked

12. (4pts) Consider a correlation between childhood obesity and a diet high in “fast food” products. If lack of exercise (not fast food) is the true cause of obesity, which obesity rates are expected in cells 1 & 2 of the following table? Assume that no other variables besides fast food and exercise are important. (one answer only)

		exercise:
		absent	present
fast foods in diet:	present	high obesity	(1)
fast foods in diet:	absent	(2)	low obesity

A) 1 is low, 2 is low	C) 1 is high, 2 is low
B) 1 is low, 2 is high	D) 1 is high, 2 is high

Electromagnetic Fields

13. (5 pts) Scientists currently accept which of the following models about EMFs? (It is of course possible that a model which is supported now may be rejected in the future.) MTF

(A) The intensity (strength or "brightness) of an EMF falls off quickly as one moves away from the source of the field

(B) Electromagnetic field radiation is a form of ionizing radiation.

(D) Across most studies, the typical high-EMF homes have an increased leukemia risk factor in the range of 10 or more.

(E) EMFs are easily screened out by shielded wires

(F) Alternating current generates EMFs.

Controls

14. (4 pts) The Monty Python video on penguin intelligence compared the performance of humans and penguins on an IQ exam. Consider the last test shown in that video (with the immigrants at the zoo). Mark all of the following factors that were controlled for in that IQ test shown (recall that a factor controlled for is one that is matched across the different groups being compared).

(A) inability to speak English	(C) ability to speak English	(E) species
(B) testing environment	(D) brain size

15. (6 pts) Each of rows (A)-(G) describe different treatments that could be applied to humans in testing factors that affect influenza infection rates. The treatments differ in which factors are present (indicated by “+”) or absent (-). Factor 1 is vitamins in the diet; factor 2 is vaccination; factor 3 is wearing gloves throughout the day; factor 4 is use of public transportation; factor 5 is use of public telephones.

Which two treatments would you want to compare to determine if factor 5 is correlated with differences in influenza infection rates when all other factors are controlled? In evaluating possible answers, pick any comparison that controls for all unwanted factors, and assume that these treatments differ only in the ways stated. Mark exactly two options, or option I if none apply. Each row (each option) describes a different set of conditions, so to know which factors would be applied in a treatment, you look across the row. If multiple combinations satisfy the problem, any correct combination will be accepted. (Two answers or I).

	factor
Option		1	2	3	4	5
	(A)	+	+	+	+	+
	(B)	+	+	+	-	+
	(C)	-	-	-	-	-
	(D)	-	-	-	+	-
	(E)	+	-	+	-	+
	(F)	+	-	-	-	-
	(G)	+	+	-	+	-
	(H)	+	-	+	-	-
	(I)	No combination satisfies the request

16-18. As described in the Notes, epidemiologists in Britain noted a correlation that certain cancers were more frequent among residents living near nuclear power plants than in the population at large. The following three questions pertain to this study and its implications.

16. (4pts) Which of the following models are consistent with this correlation? MTF

(A) nuclear power plant locations reduce cancer rates, but the people who live in these locations have ethnic cultures that elevate their cancer rates

(B) nuclear power plant locations have no effect on cancer rates, but the people who live in these locations have ethnic cultures that elevate their cancer rates

17. (4pts). Now suppose that we had been randomly assigning where all people live in Britain over the last 100 years, and that we still observed that residents living near nuclear power plants had higher-than-average cancer rates. (Randomly assigning where a person lives would of course be unethical. However, assume for the sake of this question that it could be done.) Which of the following models would now be consistent with this correlation? MTF

(A) nuclear power plant locations reduce cancer rates, but the people who live in these locations have ethnic cultures that elevate their cancer rates

(B) nuclear power plant locations increase cancer rates

(C) nuclear power plant locations have no effect on cancer rates, but the people who live in these locations have ethnic cultures that elevate their cancer rates

18. (3pts). It is unethical to move people around, however. So this is a case in which we must rely on correlational data. Which of the following controls eliminate the most factors in assessing the role of the radioactivity as the cause of the cancer? These three options are from the Notes. One only

(A) people living at environmentally similar sites as the power plant locations but lacking a nuclear power plant

(B) people living at sites of the power plants after the plant was built shortly before any radioactive material was brought in.

19. (5 pts) A UT student decides to evaluate the effect of a new fuel additive on her car’s gas mileage with her as driver. She carries a 5 gallon container of gasoline, and when her car runs out, empties the 5 gallons into the tank. Mileage is recorded for every 5 gallons. Every other time the 5 gallons is added, the additive is also added. This procedure is repeated for 50 episodes, so that mileage is determined across a variety of driving conditions, some in the city and some highway, with and without additive. What factors are explicitly controlled for in the design of this study? Do not infer more than is given. MTF

(A) make of automobile	(C) driver
(B) driving conditions	(D) vehicle weight (including that contributed by fuel but neglecting the weight of the additive)

Experiments

20. (5pts) Which design features were part of the personality survey? MTF

(A) explicit protocol	(C) blind	(E) manipulation (experiment)
(B) replication	(D) randomization

21. (4pts) The test of FC shown in the video was an experiment because (one only)

A) it included controls	C) it included several levels of replication	E) all of the above (A-D)
B) it was blind	D) it manipulated the normal FC environment	F) it was not an experiment

22. (3pts) Which features of ideal data apply to experiments but not correlational data? MTF

(A) blind

(B) randomization

(D) controls

23 (8pts). 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) 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.

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

(C) 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.

(D) 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.

(E) A scientist gives some AIDS patients a drug (AZT) to see if they live longer than expected..

(F) 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.

24. (6pts) Prisoners of Silence video. It will be shown later in the semester that Douglas Bicklen of Syracuse University claimed that the experimental tests of FC were not valid because they used an intimidating test environment and asked for tasks that autistic children were not good at (e.g., word-finding). Which of the following statements about the experimental design is/are sufficient to refute Bicklen's specific objection about an intimidating test environment? (consider the italicized statements above and below to be true) MTF

(A) Explicit protocol: the specification of a protocol in advance of the test minimized the chance that the test intimidated the facilitator or child. Knowing the protocol removes the intimidation.

(B) Controls: the correct response was typed when child and facilitator were shown the same picture, demonstrating that the FC setting was operating as normal; this control result overcomes the objection Bicklen raised.

(C) Replication: by asking the child/facilitator to identify more than one object/picture, Bicklen's objection was nullified (overcome), because there was time for the child/facilitator to adjust to the test environment.

(D) Random: [The video did not show whether the order of pictures was randomized.] Bicklen's objection was valid if the photos had been presented in random order; conversely, his objection would have been nullified/overcome if the pictures had been shown non-randomly -- deliberately starting with easy pictures first and progressing to difficult ones negates the intimidation.

Causal model

Cause invoke a third variable?