Q&A Hero

Q: 27+ By convention, we often reject the null hypothesis if the probability of our result, given that the null hypothesis were true, is a) greater than .95. b) less than .05. c) greater than .05. d) either b or c

Q: 26 To reject a null hypothesis for the finger tapping example in the text, we would a) calculate the probability of that result if the null hypothesis were false. b) calculate the probability of that result if the null hypothesis were true. c) compare the probabilities of that result if the null hypothesis were true and if it were false. d) reject the null hypothesis unless that subject closely resembled normal subjects.

Q: 25 In the finger tapping example in the text, we would reject the null hypothesis when a) the patient tapped too quickly. b) the patient tapped too slowly. c) the patient tapped either very quickly or very slowly. d) We would be unlikely to ever reject the null hypothesis.

Q: 24 The difference between a test comparing two means and a test comparing the frequency of two outcomes is a) the test statistics that they employ and their calculation. b) the logic behind the two different hypothesis testing procedures. c) the way we go about drawing conclusions from the tests. d) all of the above

Q: 23+ We are most likely to reject a null hypothesis if the test statistic we compute is a) very small. b) quite extreme. c) what we would expect if the null hypothesis were true. d) equal to the number of observations in the sample.

Q: 22 Most psychological research is undertaken with the hope of a) proving the null hypothesis. b) proving the alternative hypothesis. c) rejecting the null hypothesis. d) discovering ultimate truth.

Q: 21 What is a major advantage of using null hypotheses? a) The null hypothesis gives us a starting point. b) If the null hypothesis is false, that provides evidence for an alternative hypothesis. c) We have procedures for testing null hypotheses. d) all of the above

Q: 20 Whether or not we reject the null hypothesis depends on a) the probability of the result given the null hypothesis is true. b) how far the data depart from what we would expect if the null hypothesis were true. c) the size of some test statistic. d) all of the above

Q: 19+ If the data are reasonably consistent with the null hypothesis, we are likely to a) accept the alternative hypothesis. b) reject the null hypothesis. c) retain the null hypothesis. d) accept the null hypothesis.

Q: 18+ Which of the following is a statement of H1?

Q: 17+ Which of the following is most likely to represent a statement of the null hypothesis?

Q: 16 The basic reason for running an experiment is usually to a) reject the null hypothesis. b) reject the experimental hypothesis. c) reject the research hypothesis. d) find a non-significant difference.

Q: 15 The hypothesis that we are trying to support by running an experiment is often called a) the null hypothesis. b) the test hypothesis. c) the sample hypothesis. d) the research hypothesis.

Q: 14 Sampling distributions help us test hypotheses about means by a) telling us exactly what the population mean is. b) telling us how variable the population is. c) telling us what kinds of means to expect if the null hypothesis is true. d) telling us what kinds of means to expect if the null hypothesis is false.

Q: 13 The sampling distribution of the mean that you saw in the text a) resembled a normal distribution. b) was very skewed. c) had a mean that was unusually large relative to the population mean. d) had little to do with the population mean.

Q: 12+ To look at the sampling distribution of the mean we would a) calculate a mean and compare it to the standard deviation. b) calculate a mean and compare it to the standard error. c) calculate many means and plot them. d) look the sampling distribution up in a book.

Q: 11 The standard deviation of a sampling distribution is known as a) the standard error. b) the variance. c) error. d) the sampling deviation.

Q: 10 If I calculate the probability of obtaining a particular outcome when the null hypothesis is true, I must deal with a) the outcome. b) a sampling distribution. c) conditional probability. d) all of the above

Q: 9+ The central feature of all hypothesis testing procedures is a) the sample mean. b) a sampling distribution. c) a range of outcomes. d) the type of experiment we run.

Q: 8 If we were to repeat an experiment a large number of times and calculate a statistic such as the mean for each experiment, the distribution of these statistics would be called a) the distributional distribution b) the error distribution. c) the sampling distribution. d) the test outcome.

Q: 7+ The basic idea behind hypothesis testing a) depends on the kind of test you want to run. b) has little to do with whatever data you collect. c) is largely the same across a wide variety of procedures. d) is important only if you want to compare two populations.

Q: 6 We are more likely to declare two populations to be different if a) the means of our samples are very different. b) the variability of our samples is very large. c) the samples are normally distributed. d) all of the above

Q: 5+ Another name for sampling error is a) variability due to chance. b) error variance. c) constancy. d) both a and b

Q: 4 In hypothesis testing our job would be much easier if a) sample statistics accurately reflected population parameters. b) subjects didn"t vary so much from one another. c) we knew the population values. d) all of the above

Q: 3 In testing hypotheses we have to take into account a) sample means. b) random variability. c) differences from one set of data to another. d) all of the above

Q: 2 One of the problems we face when we try to draw conclusions from data is that we have to deal with a) means. b) error variance. c) population size. d) hypotheses.

Q: 1 Hypothesis testing is necessarily part of a) descriptive statistics. b) order statistics. c) test construction statistics. d) inferential statistics.

Q: 40 When two teams compete against each other, the result for Team A can be win, draw, or lose. These events are a) independent. b) exhaustive. c) joint. d) conditional.

Q: 39 We might find that 65% of women report themselves to be politically liberal, while only 52% of men report that they are liberal. The proportions would be described as a) erroneous. b) biased. c) conditional on gender. d) independent.

Q: 38 p(getting a job | knowing the manager) is the notation for the probability of a) getting a job or knowing the manager. b) getting a job and knowing the manager. c) getting a job given that you know the manager. d) getting a job and not knowing what to give the manager.

Q: 37 If a set of events contains all of the possible outcomes, it is said to be a) mutually exclusive. b) independent. c) dependent. d) exhaustive.

Q: 36+ The events most likely to be mutually exclusive are a) ages. b) club memberships. c) your sex and the sex of your siblings. d) none of the above

Q: 35 Given a normal distribution of intelligence test scores (mean=100, s.d.=15), what is the probability that someone will score between 100 and 115? a) cannot be determined b) .15 c) .68 d) .34

Q: 34+ If Brian has a 50% chance of getting a job, and that job would either be at IBM or AT&T, what is the probability that he will soon be working at IBM?a) .50 2 = .25b) .50 - p(AT&T)c) .50 - p(IBM)d) .50 p(AT&T)

Q: 33+ Which of the following events are most likely to be independent? a) your score on your biology midterm and your score on the biology final b) your mother's attitudes about religion and your father's attitudes about religion c) the sex of your cousin's first child and the sex of your cousin's second child d) your philosophy professor's opinion on the meaning of life and your subsequent opinion on the meaning of life

Q: 32 Which of the following is NOT a joint probability? a) the probability that you will have a hyperactive child who is a boy b) the probability that you will have a hyperactive child who is a girl c) the probability that your child will be hyperactive given that she is a girl d) the probability that you live near the ocean and that you enjoy sailing

Q: 31+ If I am drawing observations out of a hat while sampling with replacement, the probability of drawing a certain outcome a) remains constant across all draws. b) changes as I continue drawing objects. c) decreases as I continue to draw objects. d) none of the above

Q: 30 When we sample with replacement we a) only use subjects who have been selected on two separate occasions. b) put the outcome back in the pool before sampling again. c) hold all outcomes out of the pool once they have been drawn. d) have probabilities that change after each draw.

Q: 29+ With continuous variables we a) cannot estimate probabilities because they are undefined. b) need to speak about the probability of falling within a defined interval. c) can only speak about probabilities as subjective probabilities. d) can only calculate probabilities in whole units.

Q: 28 For which kind of variable is the ordinate of a graph labeled as "density?" a) a discrete variable b) a positively skewed variable c) a continuous variable d) an independent variable

Q: 27+ Which of the following is most likely to be a discrete variable? a) the temperature outside your window b) the number of courses you will take in college c) the length of time you can hold your breath d) the speed with which you can perform a task

Q: 26 A continuous variable is one that a) can take on any value between two specified limits. b) we cannot estimate. c) can take on a limited number of possible values. d) can take on any value between -ï‚¥ and +ï‚¥.

Q: 25 A discrete variable is one that a) is kept a secret. b) we cannot estimate. c) can take on a limited number of possible values. d) can take on any value between -ï‚¥ and +ï‚¥.

Q: 24 Two events are said to be independent if a) the occurrence of one precludes the occurrence of the other. b) the occurrence of both is impossible. c) both events happen simultaneously. d) the occurrence of one has no effect on the probability of the occurrence of the other.

Q: 23+ I would like to calculate the probability that you will do well in this course if you are a member of a group of students who study together. The most important word in that last sentence is a) "if." b) "calculate." c) "I." d) "study."

Q: 22 The vertical bar "|" is read as _______ when we are talking about probabilities. a) "absolute" b) "not" c) "divide" d) "given"

Q: 21 When we are talking about joint probabilities we are likely to invoke a) the multiplicative rule. b) the additive rule. c) the subjective probability rule. d) the law of joint probabilities.

Q: 20 If I am interested in the probability that you will be depressed if you have experienced a great deal of stress in the past month, I am talking about a) independence. b) a joint probability. c) a conditional probability. d) an additive probability.

Q: 19+ If I am interested in the probability that you will be depressed and that you will have experienced a great deal of stress in the past month, I am talking about a) independence. b) a joint probability. c) a conditional probability. d) an additive probability.

Q: 18 One difference between the additive and the multiplicative rules that helps us remember when to use which is a) with the additive rule we are talking about the occurrence of one of several outcomes. b) with the multiplicative rule we are talking about the occurrence of more than one kind of outcome. c) the two rules are interchangeable. d) both a and b

Q: 17 Once again using the example about supermarket fliers, we would have evidence that the "don"t litter" message on the flier was effective if we found that a) the probability of finding a flier with the message in the trash can was substantially higher than the probability calculated on the assumption that the two events were independent. b) the probability of finding a flier with the message in the trash can was substantially lower than the probability calculated on the assumption that the two events were independent. c) the probability of finding a flier with the message in the trash can was the same as the probability calculated on the assumption that the two events were independent. d) We can"t tell from the information available.

Q: 16+ Using the example from the text about the supermarket fliers, when we calculate the probability that a flier will be left either among the canned goods or in the bottom of the shopping cart, we need to invoke a) the additive rule. b) the superlative rule. c) the dependence rule. d) the multiplicative rule.

Q: 15+ Using an example from the text, when we calculate the probability that a supermarket flier will be left among the canned goods if it contains a notice not to litter, we will be dealing with a) the additive rule. b) the superlative rule. c) the dependence rule. d) conditional probabilities.

Q: 14 When we want to calculate the probability of the joint occurrence of two or more independent events, we invoke a) the multiplicative rule. b) the additive rule. c) the sum of independent probabilities. d) Bernoulli's rule.

Q: 13 An exhaustive set of events is one which a) we can never estimate. b) contains all possible outcomes. c) contains only independent events. d) comes from running a very long series of sampling studies.

Q: 12+ Two events are mutually exclusive when a) the occurrence of one event is independent of the occurrence of the other. b) the occurrence of one event precludes the occurrence of the other. c) both events are equally likely. d) the first event precedes the second event.

Q: 11 To estimate that probability that the next vehicle to leave the parking lot will be a silver pickup, we first need to a) assume that the color and the type of vehicle are mutually exclusive. b) assume that the color and the type of vehicle are independent. c) assume that the color and the type of vehicle are exhaustive. d) simply multiply the two probabilities.

Q: 10 In the parking lot below me, 40% of the vehicles are silver, and about 25% of the vehicles are pickup trucks. The probability that the next vehicle to leave the parking lot will be a silver pickup is a) .40 b) .65 c) .10 d) It can"t be estimated without knowing that color and type of vehicle are independent.

Q: 9+ I am looking down on a parking lot, and can see that about 10% of the cars are red and about 15% of the cars are blue. To estimate the probability that the next car to leave the lot will be red or blue, I would a) add those two percentages. b) multiply those two percentages. c) count the number of green cars. d) It can"t be estimated from the information provided.

Q: 8 Following up on the preceding question, suppose that you found that 27 of the new hires were women. You would probably be justified in concluding that a) there was discrimination against men. b) there was discrimination against women. c) there was no discrimination on the basis of gender. d) we don"t have enough information to even start to answer the question.

Q: 7 Last year there were 300 new Ph.D.s in chemistry looking for academic jobs. Of those, 100 were women and 200 were men. Nationwide last year there were 75 new hirings in chemistry departments. How many of those new hires would be expected to be women if there was no gender discrimination? a) 15 b) 20 c) 25 d) 50

Q: 6+ Out of a pool of 40 men and 10 women, all of whom are equally qualified for one position as an instructor in chemistry, the person hired was a male. The probability that this would happen if the department ignored gender as a variable in selection is a) .40 b) .80 c) .50 d) .63

Q: 5 Of 50 women treated for breast cancer in the local cancer unit, 35 of them survived for at least 5 years. For a woman who has just been diagnosed with breast cancer, our best guess is that the probability that she will survive for 5 years is a) 35/50 = .70 b) 15/35= .43 c) 35/100 = .35 d) we don"t have enough information.

Q: 4 Which of the following is NOT a way of setting probabilities? a) the analytic view b) the frequentistic view c) the subjective view d) the correlational view

Q: 3+ A frequentistic approach to probability is likely to be invoked a) in predicting the weather. b) in calculating the chances of winning in craps. c) in estimating the probability that a sharpshooter will score a bull's eye. d) in blackjack.

Q: 2+ Where is "subjective probability" most likely to be invoked? a) in setting the point spread in football b) in deciding if tomorrow will be a good day c) in calculating your best strategy in poker d) in playing Russian roulette

Q: 1 Which of the following is NOT an appropriate use of probability? a) estimating the likelihood that a particular event will occur b) calculating your chances of winning the lottery c) placing bets at the track d) knowing what event will happen next

Q: 61 A professor rated how frequently students actively participated in class and then calculated the probability of getting various grades broken down by participation. The data follow: A B C D FFrequently .06 .20 .03 .01 .00Sometimes .03 .12 .20 .03 .02Rarely/Never .01 .08 .07 .06 .08a) What is the simple probability of getting an A?b) What is the probability of getting an A given the student participated frequently?c) What is the simple probability of failing?d) What is the probability of failing given the student participated rarely/never?

Q: 60 A local private school is selling raffle tickets for a new sports car. They plan to sell 10,000 tickets. a) What is the probability that you will win if you bought 1 ticket? b) How many tickets are needed to have a .25 probability of winning?

Q: 59 A kindergarten teacher assigns chores to her students on a weekly basis. One student works on each task, and each student is assigned only one task a week. During the first week of school, there were 20 students and 7 tasks. Also, 4 of the students had brown hair. a) What is the probability that a student would not be assigned a chore? b) What is the probability that a student had brown hair? c) What is the probability that a student had brown hair or had a chore? d) What is the probability that a student had brown hair and a chore?

Q: 58 If the average score on the Graduate Record Exam was 500 and the standard deviation was 100, what is the probability that a random student would score between 400 and 600?

Q: 57 A safety agency was interested in whether penalties for talking on a cell phone while driving reduce the probability that individuals will DO SO. They randomly contacted 100 cell phone users. Fifty were from a state that had a law prohibiting this behavior, and 50 were from a state that had no such law. The data follow: Use Cell Phone While Driving Do Not Use Cell Phone While Driving TotalLaw 10 40 50No Law 20 30 50Total 30 70 100a) Calculate the simple probability that someone uses a cell phone while driving.b) Calculate the joint probability that someone is in a state without the law and uses their cell phone while driving.c) Calculate the probability that someone will use their cell phone while driving given they live in state with the law.

Q: 56 Imagine the same bag of marbles, but this time, marbles are NOT returned to the bag after each draw. a) What is the probability of drawing 3 clear marbles in 3 draws? b) What is the probability of drawing a clear marble, then a green, and then a clear? c) What is the probability of not selecting any clear marbles in three draws?

Q: 55 A bag of 100 marbles contains 30 blue marbles, 25 green marbles, 25 mixed green/blue marbles, and 20 clear marbles. Marbles are returned to the bag after every draw. a) What is the probability of selecting a blue marble? b) What is the probability of selecting a blue or green marble? c) What is the probability of selecting a marble that is not clear? d) What is the probability of selecting a blue marble on the first draw and then a clear marble on the second draw?

Q: 54 Your friend plays the lottery every day. Since he has never won, he is convinced that the odds that he will win next time are even better. From a probability perspective, what is wrong with your friend's logic?

Q: 53 Explain why it is important to know if someone is sampling with or without replacement when calculating the probability of multiple events.

Q: 52 Identify each of the following examples as the analytic, relative frequency, or subjective view of probability based on the example of a brother and sister playing scrabble: a) If the brother and sister are equally matched, there is a .50 probability that each will win the game. b) If the sister won 3 of the last 4 games, the probability that she will win this one is .75. c) The brother believes there is an 80% chance that he will beat his sister this time.

Q: 51 The probability that an event will occur ranges from "1 to 1.

Q: 50 The probability that a student is a Psychology major given that she is female is an example of joint probability.

Q: 49 If the probability is .90 that a student taking this class is a Psychology major, and the probability that a student in this class has red hair is .05, then the joint probability of being a Psychology major and a red head in this class is .95.