Exam 1, Biology 301C, 14 September 1998

Exam 3, Biology 301D, 13 November 2002 Printed name (required) ________________

104 points possible

1. (4 pts.)

(2pts) Key Code: Fill in (A) and (B) on scantron question 1. to indicate your exam code.

(2pts) Social security number and name. Bubble in the scantron with your name and your social security number (your SSN goes in the first 9 bubbles of the scantron ID field).

Put your name on this hard copy, or you may not get credit for taking the exam.

When finished, turn in both the Scantron and hard copy. You may write on this hard copy, but your grade will be determined by the Scantron form, provided we can find a hard copy from you.

None, one, all, or any combination of individual answers may apply to a question unless stated otherwise. We use the acronym “NOM” for “None, One, or Many.”

As usual, phrases in italics may be taken as true.

Turn in your exams by the end of the hour. A penalty may be assigned for late exams.
The language of evaluation and interpretation

2. (7 pts) The following statements pertain to the introductory lecture on evaluation. Which are true? (NOM).

(A) A model is considered to be refuted (rejected) if the data are inconsistent with it.

(B) Data that do not support a model cannot then be consistent with that model.

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

(E) A null model is part of every properly designed study. If a study lacks a null model, then it has not been properly designed.

(F) A null model is the same as a control for a study.

(G) If you are not registered for CPS in this class, then a record of your attendance will be irrelevant to your grade.

Correlations

3. (5 pts) Which options describe non-zero correlations (=any correlation that is defined but is not zero)? NOM

(A) Students are more anxious and likely to pack up books just before end of the lecture hour than at its beginning

(B) People living in shelters for the homeless are more likely to have TB than people not living in the shelters

4. (5 pts) Which points about correlations are true? NOM

(A) Simple correlations are consistent with many causal models

(B) A zero correlation between X and Y means that neither X nor Y varies

(C) If we know the strength of the correlation between variables X and Y, then we know how the average value of Y tends to change as X changes

(D) It is not possible to determine whether a correlation exists when one of the variables is “country of residence,” because a value cannot be assigned to this kind of variable.

5-7. (3 points each) Researchers have discovered that heart disease is lower in France than in the U.S. One suspected cause of this difference is wine consumption, because daily wine consumption is much higher in France than in the U.S. There have thus been proposals for people in the US to increase wine consumption as a way of reducing heart disease in the US.

Use the following variables: Variable 1: country (France versus U.S.)

Variable 2: incidence of heart disease

Variable 3: incidence of wine consumption

For each of the following questions, you are given a pair of these variables. You are asked to choose among the following 3 options that best characterizes their relationship in the problem description above.

(A) no correlation or causation is indicated.

(B) a correlation is indicated, but no causation between the variables is suggested

For each pair of variables given below, which option applies (one answer each)?

5. Variables 1 & 2: (A) (B) (C)

6. Variables 1 & 3: (A) (B) (C)

7. Variables 2 & 3: (A) (B) (C)

8. (6 points) Which of the following constitutes an example of inferring causation from correlation (i.e., 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 (the reverse of what we want).

(A) From your experimental work on brain biochemistry, you discover that a substance found naturally in one herb (spice) causes people to stay awake. You thus seek to find out if people who eat this herb do indeed sleep less. You conduct a survey in one store by interviewing people at the checkout stand and find that people who were buying this herb on the day of your survey reported 1 hour less sleep per night on average (in previous weeks) than people who were not purchasing this herb.

(B) You read in the newspaper than high fat diets are associated with heart disease. Since your diet has been high in fat, you start purchasing foods low in fat, on the hunch that your risk for heart disease will decline.

(C) 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.

(D) Drinking alcohol impairs a person's coordination. As a consequence, drunk drivers are involved in auto accidents more often than are sober drivers.

9. (5 pts) Across different cities, you observe a negative correlation between levels of tooth decay and the amount of fluoride in the city’s water supply (more tooth decay with lower fluoride). Which of the following models are consistent with this observation (meaning which models are not refuted by the correlation)?

(A) High fluoride causes lower tooth decay rates.

(B) High fluoride causes higher tooth decay rates.

(D) Cities with low fluoride have poorer economies, such that fewer people are able to afford preventative dental care than in cities with high fluoride. The cause of difference in tooth decay rates is access to dental care.

(E) Cities with high tooth decay rates tend to have high fluoride content in the water

(F) Cities with high tooth decay rates tend to have low fluoride content in the water

Controls

10. (6 pts) Each of rows (A)-(F) describe different treatments that could be applied to humans in generating data on heart disease. The treatments differ in which factors are present (indicated by “+”) or absent (-). Factor 1 is the use of a cholesterol-lowering drug (statins); factor 2 is a diet low in saturated fat; factor 3 is moderate exercise; factor 4 is a diet with daily fish oil; factor 5 is one ounce per day of alcohol.

Which two treatments would you want to compare to determine if factor 1 is correlated with differences in heart disease when all other factors are controlled? In evaluating possible answers, pick the comparison that controls for all unwanted factors, and assume that these six treatments differ only in the ways stated. Mark exactly two options, or none 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. (Two answers or None).

	factor
Option		1	2	3	4	5
	(A)	+	-	+	+	+
	(B)	-	-	-	+	+
	(C)	+	+	+	-	+
	(D)	-	-	+	+	-
	(E)	-	-	-	-	+
	(F)	+	-	+	-	+

11. (5 pts) Mark all of the following statements about controls that are correct (none, one, many)

(A) Controls are present in any non-zero correlation.

(B) To establish a correlation between fluoride and tooth decay, the control group must have a zero level of fluoride.

(D) The choice of subjects randomly guarantees that a control is present.

(E) Controls are absent from correlational data if the data are gathered prior to any manipulation

12. (6 pts) A psychologist does a survey to study correlates of criminal behavior, testing in particular whether family income level influences the propensity toward criminal behavior. The study uses pairs of identical twins, all males, who had been separated at birth and raised in different households (one twin was raised by different adoptive parents than the other); criminal records are compared between the twin in the lower-income household and the twin in the higher-income household. What factors are explicitly controlled for in this study?

(A) twin gender/sex	(D) economic level of the biological parents	(G) Time of year born
(B) neighborhood in which the twin was raised	(E) economic level of the foster parents
(C) performance in school	(F) method of discipline used by foster parents

Experiments

13. (6 pts). Which of the following studies describe experiments, regardless of whether the experiment was designed well or poorly? Some of these studies might be considered unethical, but the question is merely about which studies are experiments? (none, one, many)

(A) A scientist wishing to determine whether a certain herb decreases sleep duration goes to a store that sells the herb. This scientist asks each customer how long they typically slept in the previous month and then asks the customer how much of this herb he/she purchased in the past month. These data are then used to test the model that the herb reduces sleep duration.

(B) A UT student evaluates the effect of a new fuel additive on her car’s gas mileage. 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. The 5 gallon container (and hence the fuel tank) is alternately filled with fuel that lacks the additive and then with fuel containing the additive.

(C) To determine whether facial circulation increases when lying, you measure the facial infrared emission in 20 students. You first instruct the students to tell the truth, record their emission, then tell the students to lie, recording their emission again.

(D) A study of 100,000 nurses records the diets, weight and height of each nurse, and then follows these nurses for five years, determining which die of heart disease. The study design does not involve asking the nurses to alter their diets. The study finds that overweight women die more frequently of heart disease.

14. (7 pts) Prisoners of Silence. In a segment of this video yet to be shown, some parents and administrators had a strong vested interest in believing that Facilitated Communication works. They did not readily accept the test results which suggested that the facilitator was controlling the typing. One suggested criticism these doubters raise is that the test environment did not accurately reflect the normal FC environment (it was "intimidating"), hence the children could not be expected to perform well during the test. Which of the following options are either legitimate criticisms of the test or are legitimate defenses of the test, taking into account the outcomes of the test? None, one, or many answers.

If any part of an option is incorrect, consider the option incorrect and do not mark it.

(A) Experiment: the reason that these tests are considered experiments is because they prevented the facilitator from knowing what answer was expected. Under normal FC conditions, the facilitator and child had access to the same information.

(B) Explicit protocol: the use of any explicit protocol, as opposed to using an informal testing environment, is a valid basis for arguing that the testing environment was intimidating. However, results obtained without an explicit protocol would not generally be trustworthy.

(C) Replication: the only replication described in the video was of multiple pictures shown to the same facilitator-child pair. The negative results were thus not adequately replicated to warrant rejection of valid communication with FC.

(D) Controls: In addressing the concerns about an intimidating test environment, the best control for this kind of study would be to use each child with a familiar facilitator and also with an unfamiliar facilitator, to control for the possible intimidating effect of an unfamiliar facilitator.

(E) Controls: the controls for the picture identification tests were the cases in which the child and facilitator were shown the same photo; the fact that the correct response was typed in these cases demonstrates that the FC setting was operating as expected. If the wrong responses had been obtained with these controls, the criticism of an intimidating testing environment would have had merit.

(F) Blind: Blind: the use of blind was unnecessary in assessing communication, yet the blind feature of the study contributed the most to intimidation because the child did not know what was expected.

15. (5 pts) This question refers to the "Secrets of the Psychics" video (featuring James Randi and the palm reader Ray Hayman), and specifically to the first two experiments described (horoscopes and palm reading). Which statements about design features are true? Some options address both experiments, some only one. This question omits any reference to the experiment with the Moscow picture psychics.

(A) Both experiments clearly involved replication at some level

(B) Both experiments clearly included blind features in the design

(C) The (implied) control group for the palm reading experiment was the group of people to whom Ray had previously given palm readings by the book.

(D) The comparison of reactions from different students to the same horoscope provides a valid control for the study if we assume that the students in class would not all have had the same “true” horoscopes.

(E) The results of the palm reading experiment led the palm reader (Ray) to reject his model that a person’s response to palm reading reflected the accuracy of the reading. In other words, the data from his experiment were inconsistent with the model.

16. (5 pts) Which statements about design features applied to the personality profile study done in our 301D class?

(A) Control: The control for the study was a personality description according to the data supplied and was provided only to 1/3 of the participating students; the treatment was a personality description the opposite of what should have been stated and was given to the other 2/3 of the students.

(B) Replication: The study (in basic form) was replicated in several ways: multiple students, multiple sections of the class, multiple years.

(C) Blind: Blind was not a feature of the experiment because every student was allowed to read their personality profile and thus knew the contents before providing an assessment.

(D) Randomization: given the way that the study was conducted, with everyone receiving the same profile, randomization was not needed in assigning the profiles to students.

(E) Outcome: The most common response to the personality profile description was that the description was a mildly accurate fit to their personality (+1 on a scale from –5 to +5).

17, 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 two questions pertain to this study and its implications.

17. (4pts) Which of the following models are consistent with this correlation? (none, one, or many)

(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

18. (4pts). Now suppose that we had been randomly assigning where 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? (none, one, or many)

(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

Intrinsic Difficulties

19-23 (3 pts each). These questions ask for the course theme(s) best illustrated by the given statement. Do not assume any more than what is explicitly given in the question. That is, address only the difficulties specifically mentioned. There are fewer options here than on some practice questions. (One or many)

(A)

Rare events are difficult to quantify

(B)

Time lags slow progress

(C)

Complexity (interactions)

(D)

Humans make difficult experimental subjects

(E)

None

19. (3pts) The daughters of women who took DES during pregnancy acquired cancer more often than did the daughters of women who did not take this drug during pregnancy. However, these cancer cases generally did not appear until these offspring were twenty to thirty years old. Consequently, DES -- a harmful drug -- was used for several decades before the harmful effect was discovered.

(A) (B) (C) (D) (E)

20. (3pts) Lifespan shows numerous correlations with diet and health, but it is difficult to identify cause and effect. First, it is difficult or impossible to do the necessary experiments with humans because of cost and compliance issues. Second, it may take decades to observe the effect of someone’s diet today. And there are potentially hundreds of problems caused by the fact that the effect of one item in a diet (e.g., fat content) depends on what else is in the diet. Thus, one should not hope for a speedy understanding of what kinds of foods provide the greatest longevity.

(A) (B) (C) (D) (E)

21. (3pts) Small towns may be the victims of undiagnosed health hazards from various types of industrial pollution, because there are not enough people living in them to show statistically meaningful increases in disease rates.

(A) (B) (C) (D) (E)

22. (3pts) Sometimes scientists are simply unable to directly observe and measure what interests them. For example, before spacecraft became available, nobody knew what the back side of the moon looked like. And even today, scientists have no rock samples from deep inside the earth; the deepest bore-holes do not come anywhere near the center of the earth. In a similar vein, standard medical diagnostic procedures are generally ineffective for very obese patients, because their fatty tissue simply obscures the doctor from observing what they need to see.

These three examples all demonstrate the same impediment(s) to scientific progress. Which is/are demonstrated? Base your answer narrowly on the information given above. Mark none, one, or more than one answer

(A) (B) (C) (D) (E)

23. (3pts) It is thought that global mean temperature will increase several decades after atmospheric carbon dioxide increases. In addition, there are several factors to consider in predicting what the level of atmospheric carbon dioxide will be, including burning of tropical forests, automobile emissions, emissions from factories, and the ability of oceans to absorb atmospheric carbon dioxide. We understand many of these factors reasonably well within a country (i.e. we know how much carbon dioxide autos in the US emit), but it has proved difficult to predict how the contributions from different factors and different countries combine to produce the overall level of atmospheric carbon dioxide.

(A) (B) (C) (D) (E)

Turn in your exams by the end of the hour. A penalty may be assigned for late exams. The language of evaluation and interpretation

Turn in your exams by the end of the hour. A penalty may be assigned for late exams.
The language of evaluation and interpretation