Exam 2, Biology 301D, 18 October 2000 Printed name ________________

 100 pts; 7 pages; 22 questions

 When finished, turn in both the Scantron and hard copy. You may write on this hard copy, but your grade will be determined by is on the Scantron form.

 

None, one, all, or any combination of individual answers may apply to a question unless stated otherwise.

 

1. (2 pts.)

Social security number and name. Fill in the scantron form with the correct bubbles for your name and social security number. (For good measure, put your name on this hard copy too.)

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

 

 

Data: Error

(2-5). For each of the following descriptions, indicate the types of error present (the italicized phrase identifies the error). Mark a type of error only if it is definitely present. Do not assume any more than what is explicitly mentioned in the problem. One answer only for each question.

(A) Rounding, Precision and accuracy

Types of Error:

(B) Sampling

 

(C) Human and technical

(D) Bias

2. (4 pts) UT Traffic and Parking does a survey to determine how many parking stickers to sell for the F16 lot. They first determine that the time of maximum use is Tuesday afternoon, from 2:00-4:00. They then do a survey in the current year of usage during this time: how many of the parking spaces are available during that afternoon interval. Over a period of months, they determine that the number of available slots ranges from 0 to 15, with an average of 10. What type of error is represented by the variation from 0-15 around the average of 10? (one only)

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

3. (4 pts) It was claimed in class that choosing a subset of names out of the phone book by selecting people with the same first letter of their last name was not ensured of giving a random selection of people in the phone book. If this advice is correct, what type of error would be present when someone used that method in attempting to select people at random? (one only)

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

4. (4 pts) A few bridges in and around Austin have large colonies of bats. If a bat is picked up from the ground under a bridge (unable to fly), it has about a 2/3 chance of being rabid. If a hanging bat is pulled from the cracks in the bridge above ground, where the colony roosts, it has only about a 1 in 200 chance of being rabid. What type of error is represented by the consistent difference in incidence of rabies in bats picked up off the ground versus bats taken from the bridge ? (one only)

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

5. (4 pts) In the coin flip demonstration in class, most students observed more or fewer than the average 5 heads out of 10 flips. (one only)

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

 

Ideal Data

(6-8). For each of the following statements, mark the appropriate letters that describe the data design features present. Base your answer only on the information given. That is, mark a data feature only if it is explicitly present in the problem description. One or many bubbles (unless indicated).

(A) explicit protocol

(C) standards

(E) blind

(B) replicates

(D) random

(F) none

 

6. (5 pts) A scientist wants to determine whether drinking alcohol affects college students' cognitive abilities. Two hundred college students agree to participate in his study, signing the necessary informed consent forms. All two hundred students listen to a lecture on the topic: "Mitosis, meiosis & inheritance in segmented worms." Immediately after the lecture the scientist puts into a hat 200 slips of paper, each containing the name of one student. Without looking, he then draws the names of 75 students from the hat, and gives these 75 students two beers each, which they drink immediately. The alcohol level of all 200 students is measured with a breathalyzer test, the scientist reading his (known) status every 20 trials to ensure that the machine has not drifted in its calibration. The remaining 125 students do not drink any alcohol. In one week, the scientist gives all two hundred students a multiple choice exam on the content of his lecture.

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

 

7. (4 pts) A rancher has detailed records for 1975 to 1994 on his herd of longhorn cattle. The records show the sire (father) and dam (mother) for each of several calves, as well the weight of each calf when it was sold, and the price per pound it was sold for.

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

 

8. (5pts) A middle school student decides to determine if Fridays on the 13th day of the month are unlucky. She solicits records from emergency-room hospital admissions and police arrest reports for all four Friday-the-13ths during a two year period. To establish a base-line level of expected admissions and arrests, she also obtains records from hospitals and police for the Fridays immediately before and after each Friday-the-13th. To guard against errors in her analysis of the data, she has the analysis repeated by a second person, who also does not know which group of admissions is for Friday-the-13th and which is not.

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

 

9. (4 pts) According to the discussion in lecture and the course notes, which two of the following features of ideal data are most important in reducing (unintentional) bias? (two bubbles)

(A) random (B) blind (C) replication (D) standards  

 

10-12. Do-it-yourself protocol. You are conducting an external review/test of a DNA lab.

Your job is to send two tubes to the lab, with labels. There are several options for the content of and label on a tube. You must decide which contents to send and how to label the tubes so that the features of ideal data requested in the question are present from the lab's perspective. If a tube has a person's name on it, the lab can assume that the tube contents belong to the name of the person on the label. If a tube is labeled with a number, the contents are unknown to the lab but known to you. Your options for tube contents and tube labels are:

option How the tube is labeled Actual Contents in the tube Gender Blood type

(A) Fred Jones Fred Jones's sample M A

(B) Sally Mesich Sally Mesich's sample F O

(C) John Doe John Doe's sample M AB

(D) #173 John Doe's sample M AB

(E) #311 Karen Smith's sample F B

(F) #24 Dennis Brown's sample M A

(G) #3009 Kim Harper F A

(H) #2167 Joel Sachs M B

 

In the following questions, choose two letters among options (A)-(F) to describe the two tubes that will be sent to the lab. If it is possible to satisfy the protocol, the question will require exactly two letters and only two letters -- one for each tube. Thus, the answer for a question might be (A) & (B), or it might be (D) & (F). If more than one pair of options are possible correct answers, fill in only one correct pair of options. Thus, if (A) & (B) is one acceptable answer, and (C) & (D) is another acceptable answer, fill in either (A)&(B) or (C)&(D), but not both. Alternatively, if a protocol cannot be satisfied with the options, do not fill in any blanks.

 

10. (3 pts) Choose two tubes to guarantee replication of an individual's sample without the lab's knowledge of the replication.

two or none: (A) (B) (C) (D) (E) (F) (G) (H)

 

11. (3 pts) The lab has a way to identify the gender (sex) and blood type of a sample. Make the protocol fully blind to the lab and replicated for gender but not replicated for an individual or blood type.

two or none: (A) (B) (C) (D) (E) (F) (G) (H)

 

12. (3 pts) Make the protocol fully blind to the lab and replicated for gender and blood type, but not for individual.

two or none: (A) (B) (C) (D) (E) (F) (G) (H)

 

Drug Testing

(13-15). Each of items (A) through (G) describes a feature of Department of Transportation drug tests.

(A) Each manager whose employees are tested is required to include 3 known blank samples (lacking drugs) for every 100 unknowns; managers with more than 2000 drivers must also include some samples known to contain drugs.

(B) The laboratory initially tests all samples with a rapid screen; positive samples are retested more comprehensively.

(C) When a sample is sent to the laboratory for testing, it is labeled with a code, rather than the name of the person being tested.

(D) Split sample collection is required -- the partitioning of the original sample into two vials -- so that the second sample can be retained for retesting.

(E) The rules specify that any retesting (in the event of a positive sample) is to be done by a different laboratory than did the original test.

(F) The regulations require that any driver involved in an accident be tested for drugs and alcohol.

(G) Lab results are sent to the medical review officer before being returned to the office originating the test.

13. (4 pts) Which feature(s) represent standards in some part of the drug-testing protocol? (none, one, or many)

(A) (B) (C) (D) (E) (F) (G)

 

14. (4 pts) Which feature(s), if followed, ensure that DOT drug tests of an individual's sample are done blind? (none, one, or many)

(A) (B) (C) (D) (E) (F) (G)

15. (4 pts) Which feature(s) provide replication to guard against human and technical error? (none, one, or many)

(A) (B) (C) (D) (E) (F) (G)

DNA Typing

(16, 17). The examples on DNA typing identified several violations of ideal data, often with major implications to the conclusions of the analysis. Each problem is based on a quote taken from the Book. In each case, indicate which feature(s) of ideal data collection has been violated (as was indicated in the Book). Your options are:

A. violation of or unspecified protocol

C. inadequate replication

E. not blind

B. absence of randomization

D. lack of or insufficient standards

 

16. (3 pts) In this quote from the DNA chapter on the Castro Case, which of (A)-(E) is indicated? (none, one, many)

" An attempt to identify the sex of the watch DNA had not included male DNA, so there was no way to determine if the test had correctly demonstrated that the watch DNA was female."

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

17. (3 pts) Recall the letters of the Chicago Police Dept. to FBI lab requested DNA typing of material from the suspect. In addition to requesting the DNA typing, the letters included the following:

"we feel this comparison would greatly enhance the prosecution of [name of suspect given in original letter], who was arrested after a week long crime spree."

"The suspect [name given in original letter] had just been released from the ILLINOIS DEPARTMENT OF CORRECTIONS after serving time for the same type of crime in the same area"

Which of (A)-(E) is indicated in both quotes? (one only) (A) (B) (C) (D) (E)

 

Evaluation and Interpretation

18. (9 pts) The following points pertain to the introductory lectures on evaluation. Which statements are true? (none, one, or many).

(A) If data are inconsistent with a model, they refute it.

(B) If data support a model, they are also consistent with it.

(C) Classifying data as irrelevant to a model means that the data could not possibly refute it no matter how they turned out.

(D) Data inconsistent with a model are therefore also irrelevant to it.

(E) In our legal system, when deciding the guilt versus innocence of a person, our government uses innocence as a null model. The null model is what we accept until evidence (in the trial) causes the jury to reject it.

(F) In many aspects of society (but not science), 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 from 10 individuals to millions of individuals. Science does not work this way, however, because it sets absolute standards for rejection and acceptance of models.

(G) In considering the crash of TWA flight 800, the null model discussed in class was that the cause was a bomb.

Correlations

19. (9 pts) Which of the following statements describe a (non-zero) correlation? The correlation can be positive, negative, or unsigned. Do not circle a statement for a correlation that is zero or undefined. If insufficient information is given to determine whether a correlation exists, treat it as if there is no correlation.

(A) Last year, the average score on test 2 was the same as that on test 1.

(B) There are more bars in towns with lots of churches than in towns with few churches.

(C) Snakes do not have limbs

(D)The per-person alcohol consumption is higher in Britain than in the U.S.

(E) The year 2000 has been a bad year for the stock market compared to the previous decade.

(F) Women have one more X chromosome per cell than men do.

(G) A handicap is a device used to equalize the difficulty of a task for people with different skill levels. The more skilled people are thus assigned a greater handicap.

 

20. (4 pts)The following paragraph describes a correlation between two variables. Of the variables listed below, mark the two which are correlated.

A researcher measures the size of the corpus callosum (a region of the brain) in 27 musicians and 27 non-musicians. The researcher finds that the corpus callosum is roughly 10 to 15% larger in musicians than in non-musicians. All 54 individuals in the study were right-handed males, and all 27 musicians were classical musicians (as opposed to rock or country musicians). The study did not report any differences between the musicians and non-musicians in age or amount of alcohol use.

(A) age

(B) gender (male or female)

(C) musical ability (musician, non-musician)

(D) handedness (left-handed, right-handed)

(E) musical training (rock, country, classical)

(F) size of the corpus callosum

(G) alcohol use (low, medium, high)

21. (9 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 the opposite: correlation from causation.

(A) A study shows that people with high levels of serum cholesterol get heart disease at a higher rate than those with low cholesterol. Doctors have been recommending cholesterol-lowering drugs to people with high cholesterol levels as a way of reducing their risk of heart disease.

(B) You are store manager of the Target superstore. Because total sales in ladies lingerie department are higher than total sales in sporting goods, you decide to give the manager of ladies lingerie a larger raise than the manager of the sporting goods department, to reward the ladies lingerie manager for her superior sales skills

(C) Diamond Shamrock has hundreds of stores scattered through Texas, and each store is operated by a different store manager. Diamond Shamrock surveys each of their stores, and identifies the store locations that are losing money; to increase overall profits, they then sell the stores at these locations, and transfer the managers to other positions that have opened through attrition

(D) Use of a cell phone while driving is associated with a 3-fold increase in auto accident rates. Many countries and some states now prohibit driving while calling as a way of reducing auto accidents.

(E) Studies have documented that low amounts of alcohol consumption can help prevent heart disease. Other studies document an increased rate of cancer with higher alcohol consumption. Based on these findings, a group of researchers looks for an association of heart disease with cancer rate.

 

22. (6 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.

(A) Alcohol consumption might cause cancer.

(B) Alcohol consumption is positively correlated with cancer incidence.

(C) Alcohol consumption is negatively correlated with cancer incidence.

(D) Alcohol consumption is correlated with cancer incidence.

(E) Cancer incidence is associated with alcohol consumption.

(F) Alcohol consumption does not cause cancer.

(G) Alcohol consumption causes cancer.

(H) After being diagnosed with cancer, many patients increase their alcohol intake.