Deck 7: Likelihood and Uncertainty: Understanding Probabilities

Question 1

Clever gamblers are able to use the "laws of chance" to select winning lottery numbers.

Answer 1

False

Question 2

The purchase of insurance is a type of "bet" that you hope to lose.

Answer 2

True

Question 3

When unusual events occur (e.g., you recover from a terminal illness), we can conclude that something other than luck was responsible.

Answer 3

False

Question 4

When taking a 5-alternative multiple choice test, you are as likely to get all of the questions correct just by guessing as you are to get all of the questions wrong just by guessing.

Question 5

Basketball players tend to shoot in streaks so that a player who has just made a basket is more likely to make a basket on her second throw than if she had just missed the basket.

Question 6

Your evil twin just took a college entrance exam and scored very, very low. If he takes it again, he will probably obtain an even lower score on his second try.

Question 7

Most people assess the risk of elective surgery (e.g., a "nose job") as being safer than nonelective surgery.

Question 8

If a method of contraception has a 6% failure rate, then you would expect the same probability of getting pregnant in one year of use as you would in 10 years of use.

Question 9

Suppose that your friend plans to become a professional drummer and only 2% of all people who want to become professional drummers actually achieve this goal. In addition, suppose that he has "connections," and 80% of all successful drummers have connections like his. Only 10% of unsuccessful drummers have the same sort of connections. This means that his probability of success would increase slightly above 2%.

Question 10

Differences between samples don't mean that there are real differences between the groups being sampled unless the differences are statistically significant.

Question 11

The number of ways a particular outcome can occur divided by the total number of possible outcomes is called

A) that event's total rate.
B) that event's probability.
C) that event's occurrence.
D) that event's uncertainty.

Question 12

The mistaken belief that the co-occurrence of two or more events is more likely than the occurrence of one of the events alone is called a/an

A) heuristic error.
B) conjunctive error.
C) illusory correlation.
D) gambler's fallacy.
E) None of the above

Question 13

Dr. Evil's "Rate My Professor" rating keeps getting higher, even though he tries to keep it as low as possible (he was down to 0.2!) He decides he must be getting nicer in his old age and to be meaner than ever to his statistics students this year! The change in Dr. Evil's ratings are most likely due to

A) statistical significance.
B) a median split.
C) an illusory correlation.
D) regression to the mean.
E) None of the above

Question 14

In general, when someone scores extremely high or low on some measure, she or he will tend to score closer toward the mean (average) on a second measurement. This is called

A) regression to the mean.
B) statistical significance.
C) the conjunctive error.
D) an illusory correlation.

Question 15

Predicting how you will feel in the future if a particular event occurs is called __________, and people are very __________ at it.

A) regression to the mean…..good
B) affective forecasting…..good
C) regression to the mean…..bad
D) affective forecasting…..bad
E) None of the above

Question 16

Fred plays the Lottery every week. He is very unhappy, and figures that winning the Lottery will make all his unhappiness go away. Fred is engaged in

A) regression to the mean.
B) affective forecasting.
C) the conjunctive error.
D) the gambler's fallacy.
E) None of the above

Question 17

The use of representativeness in estimating probabilities frequently leads to a neglect of

A) confidence levels.
B) inferential statistics.
C) sample size.
D) base rates.

Question 18

A risk that is __________ is often perceived to be less risky or less hazardous than other risks.

A) artificial
B) voluntary
C) observable
D) All of the above
E) None of the above

Question 19

A risk that is __________ is often perceived to be less risky or less hazardous than other risks.

A) natural
B) involuntary
C) unobservable
D) All of the above
E) None of the above

Question 20

A/an __________ is a number calculated on a sample of people.

A) likelihood
B) expected values
C) parameter
D) statistic

Question 21

Measures like the average (mean) or median of a group are called

A) measures of central tendency.
B) experimental statistics.
C) demonstrative statistics.
D) inferential statistics.

Question 22

A difference in two numbers, like the means of two groups, is statistically significant when

A) it is smaller than usual.
B) it is particularly likely to occur.
C) it is unlikely to occur by chance.
D) its probability is near .50.

Question 23

Most people assess the risk of elective surgery (e.g., a "nose job") as being safer than nonelective surgery. This example demonstrates which concept about how perceptions influence probabilities?

A) bias toward control of events
B) bias toward known events
C) regression toward the mean
D) base rate neglect

Question 24

Carlos was timing how fast his rat ran the maze. He found that rat A ran extraordinarily fast yesterday compared to the five other rats in his sample. According to the concept regression toward the mean, which of following is likely to happen tomorrow?

A) Rat A will run extraordinarily fast
B) Rat A will run at a pace more similar to the average running pace
C) Rat A will run the slowest of the sample of rats
D) Rat A will refuse to run

Question 25

Discuss the nature of the laws of chance and the long run.

Question 26

Draw a tree diagram representing the possible outcomes of 4 flips of a fair coin. Why would you be likely to be correct if you guessed a pattern of "50% heads, 50% tails"?

Question 27

Explain the conjunction error, including an example of research investigating the conjunction error.

Question 28

Julie is single woman living in southern California. She is an independent thinker and plays the piano. She regularly donates money to her local animal shelter. If I think that it is more likely that Julie has pets and is a bank teller than it is that she is just a bank teller, I am making a/an

A) heuristic error.
B) conjunctive error.
C) illusory correlation.
D) gambler's fallacy.
E) None of the above

Question 29

Personal estimates of the probability of uncertain events are called __________; mathematically determined statements about the likelihood of events with known frequencies are called __________.

A) mutual outcomes…..joint outcomes
B) conditional outcomes…..joint outcomes
C) subjective probabilities…..objective probabilities
D) objective probabilities…..subjective probabilities
E) None of the above

Question 30

The probability of an event occurring over many trials is called its __________.

A) total rate.
B) conditional probability.
C) cumulative probability.
D) uncertainty.

Question 31

Anyone can figure out the number or percentage of trials on which a particular outcome will occur, because of

A) the rules of logic.
B) the use of circle diagrams.
C) the laws of chance.
D) psychic abilities.

Question 32

Probabilities near a value of __________ represent maximum uncertainty.

A) 1
B) 25% or 75%
C) 0.5
D) 0 (zero)

Question 33

The probability of getting "heads" three times in a row in three flips of a fair coin is

A) 0.5
B) 0.25
C) 0.125
D) 0.0625

Question 34

John and Lisa have had 5 children, all girls! Given equal likelihood of a healthy pregnancy at each conception, what is the probability of having 5 female babies in a row?

A) 0.03125
B) 0.00001
C) 0.125
D) 0.00145

Question 35

Probabilities based on brief or short "runs" are similar to research results based on

A) small samples.
B) biased samples.
C) nonrepresentative samples.
D) All of the above

Question 36

The probability of two independent events occurring together is __________ __________ __________ the probability of one of those events occurring alone.

A) more likely than
B) less likely than
C) equally likely as
D) completely unrelated to
E) None of the above

Question 37

What is the probability of getting a 4 or a 6 on one roll of a single die?

A) about 3%
B) about 20%
C) about 35%
D) about 50%

Question 38

What is the probability of getting a 1, 2, 3, 4, 5, or 6 on one roll of a single die?

A) 0.3
B) 0.5
C) 0.75
D) 1

Question 39

The belief that chance processes are self-correcting is called

A) the gambler's fallacy.
B) probability ignorance.
C) overconfidence.
D) conjunction error.

Question 40

Rhonda is going to "33 Flavors" to get a double-scoop of ice cream. What is the probability that she will order Cherry Vanilla or Butterscotch?

A) 12086
B) 12055
C) 1 / 33 X 1 / 33
D) It is impossible to tell, Rhonda is very unpredictable

Question 41

Robert is going to "33 Flavors" (with Rhonda) to get a triple-scoop of ice cream. What is the probability that Robert will order Jamocha Almond Fudge, Rocky Road, and Gold Medal Ribbon?

A) 12114
B) 1/ 33 + 1 / 33 + 1 / 33
C) 1 / 33 X 1 / 33 X 1 / 33
D) It is impossible to tell, without knowing how popular those flavors are

Question 42

The probability of two independent events occurring together is called a __________ probability, while the probability of an event occurring given that another event has occurred is called a __________ probability.

A) joint…..conditional
B) conditional…..joint
C) multiple outcome…..single outcome
D) single outcome…..multiple outcome
E) None of the above

Question 43

Two or more events are __________ when the occurrence of one event does not affect the occurrence of the other events.

A) probable
B) improbable
C) mutually exclusive
D) independent
E) None of the above

Question 44

Two events are __________ when if one occurs, the other cannot occur.

A) probable
B) improbable
C) mutually exclusive
D) independent
E) None of the above

Question 45

The "or rule" can only be used when

A) possible outcomes are mutually exclusive.
B) there are more than three possible outcomes.
C) possible outcomes are dependent.
D) conditional probabilities are being considered.
E) All of the above

Question 46

Discuss the various issues affecting probabilistic assessments of risk.