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revise 2. (4pts) Why is it difficult to measure the harmful effects of the levels and types of ionizing radiation that we think is most relevant to our population? MTF A) Sample size: too few people are exposed to any dose of ionizing radiation, and we don't know who they are, making it difficult to assess the harm.
B) Animal extrapolation: rodent and other non-humans are not useful models of cancer at the radiation doses
of interest, so we cannot do useful experiments. C) Extrapolation across related hazards: there are several different physical types of radiation, their effects on humans vary, yet we must combine the different types with such measures as rad and rem. Two people exposed to the same number of rads may have received different combinations of the radiation types. D) The increase in cell phone and microwave oven use has made it more difficult to assess how much radiation our population receives. 3. (4pts) Which of the following comprise significant portions of the U.S. average background exposures to ionizing radiation ("significant" is more than 2% of U.S. average)
A) cosmic rays B) radon C) hairdryers and other household appliances
D)microwave ovens E) elements inside your body (potassium)
F) rocks and soil G) gamma rays from processed foods
19-21 (3 pts each). Fill in the blanks of the "consequences" column of the table with the best single option (most specific) from the list below the table. The question number is given in each blank. One answer only per question.
Deviation from Ideal Data lack of replication samples not processed blindly Inadequate protocols for analysis of results Your choices for consequences are:
Consequences 19. one answer only 20. one answer only 21. one answer only
(A) Improper calculation of RMP (random match probability) in some cases (B) DNA sample degradation occurs (loss of DNA quality) (C) The RMP threshold for conviction will appear to be exceeded when it is actually not exceeded (D) Allows deliberate contamination of sample (E) Sample mix-ups in a case can go undetected (E) This protocol is no longer applicable because of recent changes in DNA typing methods (F) The protocol allows for a biased willingness to accept results (G) Selective reinforcement of the prime suspect (H) The protocol increases the likelihood of sample mix-up
Bio301D Exam 2; 13 Oct 2004
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26 Questions, 6 pages
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(I) The full extent of lab error rates remains unknown (J) This protocol allows outliers of natural variation to escape detection 12 (4 pts). The goal is to determine lab human and technical error rates of DNA typing through replicated typing of the same individuals. Ten tubes from 8 people whose DNA type is unknown are sent to the lab, each labeled with its own code. Different tubes from the same person have different codes. For this goal, is the replication blind to the lab performing the typing? Why or why not? MTF A) It is blind, because the lab does not know the people from which the samples came.
B) It is not blind regardless of the labels, because the lab can figure out which samples are the same
after they do the DNA typing.
C) It is ambiguous as to whether the procedure is blind, because there are ways in which the
procedure is blind and other ways in which it is not.
D) It is not blind because there is no standard sent with the tubes.
4. (4 pts) Which of the following demonstrations were used to illustrate errors in data, and which options also correctly identify the type of error illustrated?
A) coin flip to illustrate sampling error and how to reduce sampling error
B) "choose a random odd number" to illustrate unintentional bias C) width of a dime to illustrate human and technical error D) memory test to illustrate accuracy (as a type of RPA error) Don polled two groups of people for their opinions on the Iraq war. One group consisted of 200 UT students passing by the Student Union one day; the other group consisted of 100 people in a much larger audience attending a Baptist sermon on Sunday. Attitudes were substantially different between the two groups. Don wants to rule out the possibility of bias instead of sampling error as the cause of the difference. What options describe reasonable ways to decide if his observed differences are due to sampling error rather than bias? A) Obtain another sample from non-students, non-churchgoers. If that third sample matches either of his first two samples, or if it falls between them, then he can be confident that the difference among them is sampling error. B) Obtain much larger samples from the two original groups (UT students, people attending the same church); if the difference persists, he can be confident that the difference is not sampling error. C) Perform a statistical analysis of the data; a statistical analysis will tell him whether the differences are consistent with sampling error. D) Repeat the surveys with new people at the same locations but using a different set of questions. If the original difference was due to bias rather than sampling error, the bias should go away when the questions are changed. E) Repeat the surveys with new people at the same locations, using the same numbers of people as in the original surveys. Measure the difference in responses between the two new groups and compare that to the difference in response of the old groups. The new groups should be more similar to each other than the old groups were to each other if the differences are due to sampling error. A standard (measurement control) to evaluate whether a DNA typing lab is making mistakes could consist of which of the following. Assume that the DNA type (barcode) of the sample is unknown unless indicated otherwise. "Coded" means that an identifier is attached to the sample but without the name of the person whose DNA it is; "labeled" means that the sample is labeled in some fashion which may or may not be coded. Assume that you are the one sending the standards to the lab for testing.
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A) a sample whose DNA barcode is known to you B) a coded sample of DNA C) two samples of the same DNA that you have labeled differently D) any blind sample of DNA E) any replicated sample of DNA What described in class or book constitutes a form of replication in testing for DWI impairment? A) multiple air blanks in the breathalyzer test B) multiple breath samples from the suspect C) an air blank plus the breath sample from the suspect D) multiple tests used to assess SFST performance E) a sample of known alcohol content tested by the breathalyzer F) an explicit protocol (formal procedure) for giving SFST instructions to the suspect Which in the following list constitute(s) human and technical error? A) sample mixup B) lab protocols fail to work as claimed C) outliers of natural variation D) failure to follow protocol E) deliberate contamination of a sample Which options identify a "fix" for the type of error indicated; a "fix" may either reduce that error or at least to detect that error.
A) error: sample mixup; fix: code tubes (blindly)
B) error: unintentional failure to follow protocol because it is difficult to understand; fix: design a protocol that is easier to understand but achieves the same objectives C) error: protocol; fix: D) error: lab fails to conduct assays carefully and fails to check results because they know which samples belong to the suspect and know what results are consistent with suspect being guilty. Fix: code samples so that lab does not know which belong to suspect. E) error lab occasionally declares false matches, but they often go undetected. Fix: blind proficiency tests. For the following choices, you are asked to identify one or more types of error in the problem. Your choices for those errors are: A) Sampling B) Bias C) RPA D) Human and technical E) None
Winning rates at the slot machines at two different casinos are compared for a single day. There is some difference in the average rate between the casinos. Data are then collected for a month of winnings, and the
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difference between the two casinos is greatly reduced. What type of error is (errors are) suggested by the differences in daily winning rates between the casinos? (A) (B) (C) (D) (E)
If the lab declares a match between a suspect and a crime scene sample, and there is a very small probability of a random match (e.g., 1 in a billion) but a much larger probability that the lab made a mistake and falsely declared a match (e.g., 1%), what can be said about the odds that the suspect does not match the sample? A) The odds are still close to 1/billion because there is a 99% chance that the lab did NOT make a mistake, so 0.99x1/billion is still close to 1/billion. B) The odds are close to 1%, because 1% of the time The advice given to Austin residents (circa 1985) to avoid eating more than one fish a week from Town Lake was based on a concern that fish had high doses of chlordane levels (chlordane was a pesticide used in termite treatment). The advice that eating a few fish was OK but eating several was not necessarily involves A) extrapolation across species (fish to humans) B) extrapolation across doses C) extrapolation across related hazards D) a linear extrapolation The rodent model of carcinogenesis (cancer testing of chemicals using rodents) has been challenged as having serious flaws (by Bruce Ames). That challenge is based on A) extrapolations across species (rodents to humans) B) extrapolations across doses C) extrapolations across related hazards Which examples/options fit an accelerating model of extrapolation of outcome? A) Using your accident rate when driving after no drinks as a baseline, you are 4X as likely to have an accident while driving after two drinks as after one drink B) If ATT can save $2 billion by laying off 20% of its workforce, it can save $10 billion by laying off 100%
C) Half the LD50 dose of radiation does not kill 25% of animals (the LD50 kills half).
D) A company needs to sell 10,000 products to break even (no profit) but the profit per product increases with each additional product sold. In the first days of a polio vaccine, five different labs were licensed by the gov't to make the vaccine for a massive U.S. trial (over 100,000 people received the vaccine). The vaccine was supposed to be killed poliovirus, but a small number of people who got the vaccine also got the disease, and in some of those cases, the symptoms disease were such that it seemed that the vaccine gave them the disease. Vaccine from one lab (Cutter) had a higher rate of disease than those of the other four labs, and an in depth review of the facts and procedures indicated that the Cutter vaccine did indeed cause more polio disease than if its rates had been the same on average as the other labs. In contrast, differences among the other vaccines were not considered meaningful. From this, what can be said about the difference between the Cutter vaccine disease rate and the disease rates of the four other vaccines?
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A) The higher disease rate of Cutter vaccine can be attributed to sampling error? B) Any differences among disease rates of the other vaccines can be attributed to sampling error? C) The consistent difference between Cutter disease rates and other vaccine disease rates is due to biased data. D) The company running the Lotto advertises winners to convey the impression that anyone can be a winner too. However, only winners are shown in these ads, and if winners could only be shown amongst losers in proportion to how common they were (one at time), none of us would ever watch TV long enough to see a winner. The disproportionate display of winners relative to lowers represents a type of "error" in the data, that the incidence of winners shown in the add does not match the real incidence of winners. What type of error is this? A) sampling error B) RPA C) bias D) human and technical E) blind F) standards Replication does not fix bias because A) Bias is a consistent type of error in data, so replication alone just produces more of the same B) Bias changes with each sample, so a new sample merely creates a new bias C) randomizing (which does help fix bias) is eliminated by replication The coin flip demo showed A) that, with 10 flips, most of the class failed to get even with 5% of the expected 50% heads B) that pooling the data from the entire class (and previous classes) consistently yielded results close to 50% heads (within 5% or so) C) that bias and sampling error can affect the same data You are asked to guess the number of pennies in a large jar for a prize, the only stipulation being that you cannot directly count them in any fashion. You weigh the entire bulk of pennies at 4236.74 grams and you weigh a single penny at 2.35 grams (your scale only goes to 2 decimal places). Dividing, you arrive at 1802.86 pennies in the jar, and you round it up to 1803. However, the actual number of pennies is actually 1800, and you don't win the prize. What type of error is responsible for your miscount? Some wildlife biologists are asked to sample two lakes to assess the abundance of 3 different types of fish. This procedure involves setting 10 nets and counting the fish caught in the nets. Lake Wobegon yields 250 bass, 1201 crappie, and 2013 carp Lake Reelfoot yields 803 bass, 4036 crappie and no carp.
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What type of data error can be attributed to the difference in fish numbers between the two lakes? For a technique used to declare a match between a forensic sample and a suspect, such as DNA typing, fingerprinting, or hair matching, what is the consequence of not having a reference database from the population? A) Without a reference database, it is not possible to conduct proficiency tests of lab error rates. B) Without a reference database, it is not possible to calculate a RMP (random match probability) C) Without a reference database, it is not possible to detect sample mixup D) Without a reference database, there is no benefit of blind procedures. Data: Error (8-9). Do-it-yourself protocol. You are conducting an external review/test of a genotyping 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 tube label Contents in the tube are Blood type Gender Marker from status + (A) Laura Baker Laura Baker B Female negative (B) Darin Rokyta Darin Rokyta AB Male (C) Rachael Springman Rachael Springman O Female + (D) #132 Darin Rokyta AB Male negative (E) #218 Patsy Cline A Female + negative (F) #10 Pam Hines O Female negative (G) Jerry Allison Jerry Allison B Male negative (H) #101 Brent Iverson AB Male (I) No combination of tubes can satisfy the protocol
In the following questions, choose two letters among options (A)-(H) to describe the two tubes that will be sent to the lab. The tube labels are the only information the lab receives about the samples, and the lab does not have prior information about the individuals. 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. If a factor (such as identity, blood type, gender, etc.) is not specified in the protocol, then that factor will be ignored in grading the answer.
Alternatively, if a protocol cannot be satisfied with two from (A)-(H), fill in (I). 8. (3 pts) Choose two tubes to guarantee replication of individual, marker, and blood type but gender is not replicated; the replication of individual should be blind to the lab that is, the lab should not be able to tell from the information on the tubes that the two samples have the same blood type. two tubes or I: (A) (B) (C) (D) (E) (F) (G) (H) (I) 9. (3 pts) Make the tubes replicated for marker, gender and blood type but not replicated for individual. two tubes or I: (A) (B) (C) (D) (E) (F) (G) (H) (I)
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(10-12). For each of the following statements, mark the appr...