Exam 1, Biology 301C, 14 September 1998

Data Presentation

1. (5pts). Which of the following points about the data presentation lecture and chapter are true? MTF

A) The scale of presentation: class responded differently to graphs of the same data that merely used different scales on the axes

B) Some methods of presentation have been found to cause little bias in a person’s response. One example is that the scale used to provide multiple choice options for a question does not affect the response as long as the correct answer is included in the options.

C) We considered two ways of presenting data that allow one to calculate a false positive rate in a drug test. The approach using conditional probability was more difficult to understand than the approach using natural frequencies.

D) When describing the benefit of a drug, use of relative frequencies (e.g., 50%) was said to be more favorable than absolute frequencies (e.g., 2 in 1000) for convincing people to use the drug.

Language of evaluation

2. (5pts) The following options pertain to the concept of model falsifiability. Which are true? MTF

A) We briefly discussed a newspaper article on pet psychics. It was suggested that many of the claims of a pet psychic (about how the pet feels) are not falsifiable.

B) If a model is not falsifiable, it means the same as data being irrelevant to the model.

C) If a model is not falsifiable, no data can possibly be gathered that might refute the model.

D) As shown in the video, psychic phenomena applied to humans (e.g., horoscopes, palm reading) cannot be subjected to evidence-based (scientific) evaluation – they lie outside the scientific method.

3-6. (3 pts each) Use the 4 options listed below to answer the next four questions. MTF for each

A) The data are irrelevant to the model

B) The data are inconsistent with the model

C) The data support the model

D) The data prove the model

3) Which options mean that the data could not refute the model no matter how they turned out? A B C D

4) Which options mean that the data could possibly have refuted the model but did not? A B C D

5) Of 100 models that the data might have refuted, the data refute all but one. What do we say about the relationship of the data to the one model that was not refuted? A B C D

6) Which options mean that the data refute the model? A B C D

Correlations & Causation

7. (7 pts) 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) Coffee drinkers are no more likely to have high blood pressure than are non-coffee drinkers.

(B) 98% of felons are bread eaters.

(D) Moderate alcohol drinkers have higher age-adjusted survival rates than non-drinkers

(E) Austin rainfall during the last 12 months is lower than it was during the preceding 12 months

(F) The mean in exam 2 was lower than the mean on exam 1.

(G) Death rates for skydiving are 1 in 100,000 jumps; death rates for driving are 1 in 170,000 miles driven.

8. (8 pts) 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 cause the STD rate to go down.

Which of the following models instead invoke a third variable to explain the cause of this correlation? In answering, recall that, for models that do invoke a third variable, raising taxes would not by itself cause STD rate changes. MTF

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 less promiscuous; less promiscuity causes lower STD rates	(B)
Conservative governments tend to raise ‘sin’ taxes more than liberal governments; conservative governments also cause people to behave less promiscuously; less promiscuity causes lower STD rates	(C)
Beer tax revenue is used to provide cheap health care, and the availability of health care cures more STDs	(D)

9) (4pts) Consider a correlation between college grades and belonging to a sorority/fraternity: members of these social organizations have lower grades than non-members. If grades are due to owning vs. not owning a car instead of membership, what grades are expected in cells 1 & 2 of the following table? Assume that no other variables are important. (one answer only)

		membership in frat/sorority:
		no	yes
own car:	yes	(1)	low grades
own car:	no	high grades	(2)

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

10. (6 pts) Mark all models(s) that are inconsistent with the information in the following graph. That is, mark an answer if it CAN be ruled out using the information in the following graph. Assume you have no data other than what is presented in this graph. MTF

AppleMark

You can rule out which of the following? (MTF)

(A) Family size is correlated with family income

(B) Family size is negatively correlated with family income

(D) Having a high-paying job causes an adult to be less interested in having children

(E) Having a high-paying job causes adult to be more interested in having children

(F) Red color of a car causes an elevated accident rate

11. (7 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, that infer correlation from causation, or that test the causal basis of a correlation. MTF

(A) You read that people who eat fast food have more health problems than average. You have never eaten much fast food, but this information increases your resolve to avoid fast food.

(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) A scientist observed that milk maids tended not to get smallpox. He guessed that this low incidence of smallpox was due to their exposure to cowpox, so he developed a vaccine against smallpox using the cowpox virus.

(D) Quitting the smoking habit reduces a person’s lung cancer rate. As a consequence, former smokers who have quit the habit have lower lung cancer rates than those who continue smoking.

(E) People who overeat have high levels of health problems. People who smoke have high levels of health problems. People who both overeat and smoke have the highest levels of health problems.

Controls

12. (5 pts) (As on a previous test)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). MTF

(A) inability to speak English	(D) body size
(B) ability to speak English	(E) testing environment
(C) brain size	(F) environment in which the subjects were born and raised

13. (5 pts) Each of rows (A)-(I) describe different treatments that could be applied to cornfields in attempting to maximize yield. The treatments differ in which factors are present (indicated by “+”) or absent (-). The factors are fertilizer; insecticide; herbicide; plowing before planting; use of genetically modified seeds. For each treatment, the data gathered are the pounds of corn harvested per acre (data are not shown).

Which two treatments would you want to compare to determine if insecticide is correlated with differences in corn harvested 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 J 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 J).

	factor
Option		fertilizer	insecticide	herbicide	plow	GM seeds
	(A)	+	+	+	+	+
	(B)	-	+	+	+	-
	(C)	-	-	+	-	+
	(D)	-	-	-	+	-
	(E)	-	-	-	-	-
	(F)	+	-	+	-	-
	(G)	+	+	-	-	+
	(H)	+	+	+	+	-
	(I)	-	-	+	+	-
	(J)	No combination satisfies the request

14. (6 pts) Mark all of the following statements about controls that are correct. In some options, you are asked to decide if a factor X is controlled. MTF

(A) Controls are absent from correlational data because the data are gathered prior to any manipulation

(B) To establish a correlation between blood alcohol level and car accident rate, the control group must have a zero level of blood alcohol.

(D) Factor X is controlled if X is present in the Control group and absent from the Treatment Group

(E) Factor X is controlled if X is absent from both the Control and Treatment groups

(F) Factor X is controlled if X is present in every individual in both the Control and Treatment groups

Experiments

15. (6pts) Which of the following are experiments and also test whether high stress increases the risk of cancer? MTF

A) A randomly selected group of people is asked whether they have cancer and whether they have experienced highly stressful events. These questions are part of a larger questionnaire so the people don't know the reason for the survey.

B) People are divided into two groups. One group is exposed to a highly stressful event while the other is not. The occurrence of cancer is monitored for years afterward.

C) Rats are divided into two groups. One group gets a carcinogen (cancer causing agent) while the other does not. Stress levels are then monitored in rats that have cancer and those that don't.

16. (6pts) Which options about the in-class personality survey are true? MTF

(A) It was an experiment because the survey used a blind design.

(B) It was not an experiment because there was no manipulation.

(C) Most of the Bio301 students scored the personality description of themselves as reasonably accurate (a score of 3 or better in a range of –5 to +5).

(D) Randomization. In light of the goal, the study would have been improved if the distribution of who got which survey had been randomized, both in our class and in the video.

(E) Blind was essential to the goal of the studies. If everyone had known the true purpose of the survey (and had known the design), it is likely that our class and the one shown would not have rated the personality description so highly.

17. (4pts) The test of FC shown in the video was an experiment because (one only)

A) it included controls

B) it manipulated the normal FC environment

C) it was blind

D) it included replication

E) all of the above (A-D)

18. (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 are valid in refuting Bicklen's specific objection of an intimidating test environment causing the failure? 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.

(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) Null model. One valid concern with the tests is that they are based on the null model that the child cannot communicate (i.e., the experiment is looking for positive responses). The appropriate null model should be that the child CAN communicate.

(D) Controls: The best control for this kind of study (in light of the objection raised above, and in light of the results obtained) is to use each child with a familiar facilitator and also with an unfamiliar facilitator, to control for the "intimidation" effect of an unfamiliar facilitator.

(E) Blind: the use of blind was unnecessary in assessing communication, yet the blind feature of the study contributed the most to intimidation.

19. (4pts) Which options are true about experiments? MTF

A) Experiments are able to control for unwanted variables better than correlational data

B) Only experiments, not correlational data, can be analyzed blindly

C) Experiments can control for hidden variables that have not even been identified.

D) Two types of experiments were noted, one in which the variables to be controlled for are known in advance

20. (5pts) Which are true of clinical trials with humans? MTF

A) They typically include features of blind, random, and replication.

B) If you participate in a study, you will be included all in three phases (I, II, III)

C) Clinical trials qualify as experiments on humans.

D) Clinical trials usually lack controls for ethical reasons

21. (3pts) Key code (AB), name, and EID. Fill in (A B) in scantron field 21 to indicate your key for this version of the exam.

Be sure your name and EID number are correctly bubbled in on the scantron.

Your name is required on this exam form and the scantron form to receive credit for this test.

Causal model

Third variable?