Statistics Module 2: Chapter 3-4

Using a normal curve table, if a person has a score in the bottom 42% of all scores in a distribution, the highest Z score this person can have is a) -1.41 b) -0.94 c) -0.20 d) 0.25

-0.20

The symbol for the standard deviation of a sample is a) O^2 b) SD^2 c) O d) SD

SD

A result is considered statistically significant when a) the sample score is so extreme that the research hypothesis is rejected b) the sample score is so extreme that the null hypothesis is rejected c) the population mean is so extreme that the research hypothesis is rejected d) the population mean is so extreme that the null hypothesis is rejected

The sample score is so extreme that the null hypothesis is rejected

An increasingly common way to report the results of statistical tests in a research article is a) p= 0.49 b) p> .05 c) p< .05 d) p< t

p= 0.49

The symbol used to indicate a population parameter is usually a) a greek letter b) an ordinary letter with a tilde mark (~) or hat mark (^) c) a hebrew letter d) an ordinary letter with a bar over it

A greek letter (little u with weird swish on side)

The probability rule that applies when two mutually exclusive outcomes are possible is the a) addition rule b) subtraction rule c) multiplication rule d) division rule

Addition rule

When a psychologist sets up a hypothesis testing problem, the intent is to a) determine whether the predicted behavior will occur b) determine whether the opposite of the predicted behavior will occur c) test for two effects, the predicted behavior and the opposite behavior d) test the difference between two populations, regardless of the predicted behavior

Determine whether the opposite of the predicted behavior will occur

A psychologist who states the hypothesis that there will be no difference between a new approach to therapy and the standard approach is stating a a) comparison hypothesis b) research hypothesis c) null hypothesis d) differential hypothesis

Null hypothesis

If a student wants to study alcohol use at a high school obtains a complete list of the students and has a blindfolded person select as many people as needed for the study, the student is conducting a) random selection b) haphazard selection c) specified selection d) quota selection

Random selection

An increasingly common way to report the results of statistical tests in a research article is a) p = .049 b) p < .05 c) p < .05 d) p < t

p = .049

If the mean score on a stress scale is 5, the standard deviation is 2, and the distribution is normal, the percentage of people who would obtain scores between 5 and 9 is a) 34% b) 14% + 34%= 48% c) 50% d) 34% + 34% = 68%

14% + 34% = 48%

If the sophmore class is 50% women, the junior class is 45% women, and the senior class is 55% women, the probability of drawing a woman who is a junior is a) 45% b) 50% c) 55% d) 95%

45%

If a sophomore class is 50% women, the junior class is 45% women, and the senior class is 55% women, the probability of drawing a woman who is a junior is said to be a) additive b) conditional c) multiplicative d) dependent

conditional

The normal curve is most likely to be described as a) bimodal and roughly symmetrical b) unimodal, roughly symmetrical, and bell-shaped c) skewed to the right d) a roughly symmetrical U-shape

Unimodal, roughly symmetrical, and bell-shaped

If an organizational psychologist conducts extensive interviews with 40 workers at a large factory to examine the morale among workers in general at that factory, the population is a) the 40 workers interviewed b) all the workers in the factory except the 40 interviewed c) all the workers in the factory d) all the workers necessary to create a normal distribution

All the workers in the factory. The 40 interviewed are just the sample.

The term relative frequency refers to a) the expected number of times a particular outcome of an experiment will be obtained b) the frequency of a particular result when an experiment is repeated c) the expected result if an experiment is repeated frequently d) the number of times something occurs relative to the number of times it could have occurred

The number of times something occurs relative to the number of times it could have occurred

The raw score that corresponds to a Z score of of 2.0 obtained from a distribution with a mean of 80 and a standard deviation of 10 is a) 82 b) 90 c) 100 d) 170

100

In a housing project there are 350 households in which English is spoken, 50 in which Spanish is spoken, and 100 in which the language is other than English or Spanish. If a psychologist approaches a house at random to conduct an interview, the chance that the language in that household will NOT be English is a) 1/500 = .002 b) 50/350 = .14 c) 150/500 = .3 d) 150/300 = .43

150/500 = .3

If you set alpha to .001 and are conducting a one tailed test, what do you need to look up in the normal curve table to determine the cutoff Z score on the comparison distribution? a) .005 b) .001 c) .0005 d) .0001

.001

The conventional levels of significance in hypothesis testing in psychology are a) .001 and .01 b) .01 and .05 c) .10, .20, and .30 d) .05, .25, and .95

.01 and .05

Using a normal curve table, if a person received a test score that is in the top 32% of all test scores, the person's Z score must be at least a) 0.46 b) 7.14 c) 12.55 d) 0.91

0.46

The variance of a distribution of Z scores is always a) EZ/N b) (Z) (M+SD) c) 0 d) 1

1

The traditional view about the normal curve in psychology is that normal curves are a) rare in nature, but often occur in psychological studies b) common in nature, but psychological measures rarely yield normally distributed scores c) almost guaranteed because of the way psychological measures are developed d) rare both in nature and in the distributions of scores in psychological research

Almost guaranteed because of the way psychological measures are developed

The distribution that represents the situation in which the null hypothesis is true is a) the comparison distribution b) the sample distribution c) a two tailed distribution d) a one tailed distribution

The comparison distribution

When the results of a study are not extreme enough to reject the null hypothesis, a psychologist can conclude with reasonable confidence that a) the results support the null hypothesis b) the results prove that the null hypothesis is true c) the results support the research hypothesis d) the results are inconclusive

The results are inconclusive

When psychologists study a sample to see if it represents a population (called population 1) that is different from a know population (called population 2), the comparison distribution is a) the same as the distribution of population 1 b) the same as the distribution of population 2 c) a rectangular distribution with the same mean and standard deviation as population 1 d) a rectangular distribution with the same mean and standard deviation as population 2

The same as the distribution of population 2

A one tailed test is associated with a) the research hypothesis b) the null hypothesis c) a nondirectional hypothesis d) a directional hypothesis

A directional hypothesis

When a psychologist rejects the null hypothesis at the .05 level, the results of a study indicate that a) there is less than a 5% chance of getting such an extreme result if the null hypothesis is true b) there is more than a 5% chance of getting such an extreme result if the null hypothesis is true c) there is a 5% chance that the research hypothesis is true d) there is a 95% chance that the research hypothesis is true

There is less than a 5% chance of getting such an extreme result if the null hypothesis is true

A result that is statistically significant at the .05 level would be reported in a research article as a) p = 5% b) p > .05 c) p < .05 d) p < t

p < .05

The interpretation of. a probability made my students who say there is about a 90% chance they will see a friend who has a class across the hall at the same time on any day is the a) subjective interpretation b) objective interpretation c) long-run relative-frequency interpretation d) bayesian interpretation

Subjective interpretation

If a psychologist tests whether there is any difference between how fast people work in the morning versus how fast they work in the evening the null hypothesis is that a) people who work in the morning work faster b) people who work at night work faster c) there is a difference in worker speed, but no prediction is made d) there is no difference in the speed at which people work

there is no difference in the speed at which people work

Using a normal curve table, the percentage of scores between a Z score of 1.29 and a Z score of 1.49 is a) 0.54% b) 3.04% c) 7.49% d) 83.34%

3.04% 1.49 % to mean is 43.19 1.29 % to mean is 40.15 Subtract to find what's in the middle

If the mean of a test is 13 and its standard deviation is 3, the Z score for a person with a raw score of 7 is a) -2 b) -1 c) 1 d) 2

-2

In a distribution of Z scores, the mean is always a) 10 b) 1 c) 0 d) 50

0

In a distribution of Z scores, the mean is always a) 10 b) 1 c) 0 d) 50

0

If the cutoff Z score on the comparison distribution is -1.64 and the sample Z score is 2.05 on the comparison distribution, the correct decision is to a) fail to reject the null hypothesis b) reject the null hypothesis c) accept the research hypothesis d) fail to accept the research hypothesis

Fail to reject the null hypothesis

If the cutoff Z score on the comparison distribution is 1.64 and the sample Z score is 1.32 on the comparison distribution, the correct decision is to a) fail to reject the null hypothesis b) reject the null hypothesis c) accept the research hypothesis d) reject the research hypothesis

Fail to reject the null hypothesis

The question below is based on the following scenario. Molly wants to pursue a graduate degree at New University but is unsure whether to specialize in law or medicine. To help her decide, she takes the MCAT and LSAT exams. LSAT: Molly's score = 120; Students at New University: M=150 SD=15 MCAT: Molly's score=52; Students at New University: M=40, SD = 6 Molly's Z scores were: a) LSAT, Z = 2.00; MCAT Z = 2.00 b) LSAT, Z = 2.00; MCAT Z = -2.00 c) LSAT, Z = -2.00; MCAT Z = 2.00 d) LSAT, Z = -2.00; MCAT Z = -2.00

LSAT, Z = -2.00; MCAT Z = 2.00

If a psychologist tests whether a new teaching method is more effective than the old one, the research hypothesis is that a) the new teaching method is more effective than the old teaching model b) the old teaching method is more effective than the new teaching method c) there is no difference in effectiveness of the old and new teaching methods d) there is a difference in effectiveness between the two methods, but no prediction is made

The new teaching method is more effective than the old teaching method

If a counseling psychologist wants to know if doubling the number of counseling sessions attended by students experiencing severe test anxiety will reduce or increase the amount of anxiety the students report just before a test, the statistical test the psychologist would use would be a) one tailed because only one issue is discussed - therapy sessions b) one tailed because there is only one interaction between the therapy and anxiety c) two tailed because there are two variables - whether or not students undergo therapy and how anxiety is affected d) two tailed because the direction of the effect of increasing the amount of therapy is not predicted

Two-tailed because the direction of the effect of increasing the amount of therapy is not predicted

A psychologist who rejects the null hypothesis - because the probability of obtaining the results if the null hypothesis is true is less than 5% - would express this finding in symbols as a) p = 5% b) p < .05 c) .05 < p d) p > 5%

P < .05

Using a normal curve table, if a person received a test score that is in the top 32% of all test scores, the person's Z score must be at least a) 0.46 b) 7.14 c) 12.55 d) 0.91

0.46

The decision to reject the null hypothesis using the Z test is made a) if the Z score is less than -1 or greater than 1 b) if the Z score is greater than 2.5 c) by comparing the Z score needed to reject the null hypothesis to the actual Z score of the sample d) by comparing the standard deviation of the sample (SD) to the standard deviation of the population.

By comparing the Z score needed to reject the null hypothesis to the actual Z score of the sample

The fact that probabilities are proportions mean that they a) have to be larger than one b) cannot be lower than zero or more than one c) cannot be lower than zero of more than .05 d) can be either a positive or a negative

Cannot be lower than zero or more than one

When a result is not statistically significant, the correct decision is to a) fail to reject the null hypothesis b) reject the null hypothesis c) fail to reject the research hypothesis d) reject the research hypothesis

Fail to reject the research hypothesis

The correct arguement for using a two-tailed test, even if there is a clear basis for predicting a result in a given direction, is that a) if the null hypothesis is in fact true, rejecting it will provide stronger evidence in support of it b) one-tailed tests cannot be used in most studies involving one or two groups c) if an unexpected result that is opposite of what is predicted occurs, it does not have to be ignored d) a two-tailed test improves the chance of getting a statistically significant result

If an unexpected result that is opposite of what is predicted occurs, it does not have to be ignored

The "cutoff sample score on the comparison distribution" is the point at which a) if the null hypothesis is true, a result this extreme is unlikely b) if the research hypothesis is true, a result this extreme is unlikely c) the comparison distribution ends d) the null hypothesis is accepted if the result is more extreme

If the null hypothesis is true, a result this extreme is unlikely

The correct argument for using a one-tailed test when there is a clear basis for predicting a result in a given direction is that a) the underlying mathematics of one tailed tests are more accurate b) if the result is opposite to the prediction, the researcher can still do a two tailed test later c) it is more conservative in that one tailed tests make rejecting the null hypothesis harder d) it is less conservative in that one tailed tests make rejecting the null hypothesis easier

It is less conservative in that one tailed tests make rejecting the null hypothesis easier

The interpretation of probability that explains the fact that if a person were to roll a six-sided die an infinite number of times, one would expect to get a one 1/6 of the time, a two 1/6 of the time and so on is the a) subjective interpretation b) objective interpretations c) long-run relative-frequency interpretation d) bayesian interpretation

Long-run relative-frequency interpretation

A sample's representativeness is a) more important to psychologists who are interested in relationships between variables b) more important to sociologists who are interested in a population's mean and variance c) equally important for both psychologists and sociologists d) not at all important for either psychologists or sociologists

More important to sociologists who are interested in a population's mean and variance

The most accurate statement about research articles in psychology is that a) normal curves and method of selection are occasionally mentioned, and probability is rarely discussed except in terms of statistical significance b) normal curves and probability are rarely mentioned, but the method of sampling is almost always described c) normal curves and probabilities are almost always mentioned, but populations and samples are rarely mentioned d) normal curves, populations, samples and populations are all almost always described

Normal curves and method of selection are occasionally mentioned, and probability is rarely discussed except in terms of statistical significance

If a health psychologist wants to know if regular exercise improves people's health, the type of hypothesis the psychologist would use is a) one tailed because the study is only interested in whether the exercise increases health b) one tailed because the study only looks at the effects of exercise and does not consider other factors c) two tailed because the study will have to involve both healthy and unhealthy people d) two tailed because no direction for any observed difference has been predicted

One tailed because the study is only interested in whether the exercise increases health

The first step of hypothesis testing involves specifying the a) comparison distribution b) cutoff sample score c) populations and hypotheses d) sample's score on the comparison distribution

Populations and hypotheses

If the cutoff Z score on the comparison distribution is +/- 1.96 and the sample Z score on the comparison distribution is - 2.05, the correct decision is to a) fail to reject the null hypothesis b) reject the null hypothesis c) accept the research hypothesis d) fail to accept the research hypothesis

Reject the null hypothesis

If the null hypothesis is rejected, the researcher can conclude that the results a) support the research hypothesis b) prove that the research hypothesis is true c) are inconclusive d) support the null hypothesis

Support the research hypothesis

The question below is based on the following scenario. Molly wants to pursue a graduate degree at New University but is unsure whether to specialize in law or medicine. To help her decide, she takes the MCAT and LSAT exams. LSAT: Molly's score = 120; Students at New University: M = 150, SD = 15 MCAT: Molly's score = 52; Students at New University: M = 40, SD = 6 In relation to the other people at New University, on which test did Molly get the better score? a) the LSAT b) the MCAT c) the scores were equal d) it is impossible to say without more information

The MCAT

The item below is based on the following scenario: A health psychologist is interested in the effectiveness of a anew exercise on reducing the rate of heart attacks because the exercise requires no equipment, and therefore, can be done without cost. What is the comparison distribution? a) the distribution of people who participate in the exercise program b) the distribution of people who do not participate in the exercise program c) the distribution of people who have heart attacks d) the distribution of people who do not have heart attacks

The distribution of people who do not participate in the exercise program

The item below is based on the following scenario: A health psychologist is interested in the effectiveness of a anew exercise on reducing the rate of heart attacks because the exercise requires no equipment, and therefore, can be done without cost. What is the research hypothesis? a) people will participate because it does not cost them any money b) the exercise will make a difference in the rate of heart attacks c) the exercise will reduce the rate of heart attacks d) the exercise will increase the rate of heart attacks

The exercise will reduce the rate of heart attacks

Rejecting the null hypothesis at the .05 level means that a) there is more than a 5% chance of getting such an extreme result if the null hypothesis is true b) there is more than a 95% chance of getting such an extreme result if the research hypothesis is true c) there is less than a 5% chance of getting such an extreme result if the null hypothesis is true d) there is less than a 95% chance of getting such an extreme result if the research hypothesis is true

There is less than a 5% chance of getting such an extreme result if the null hypothesis is true.

If a psychologist tests whether there is any difference between how fast people work in the morning vs. how fast they work in the evening, the null hypothesis is that a) people who work in the morning work faster b) people who work at night work faster c) there is a difference in worker speed, but no prediction is made d) there is no difference int eh speed at which people work

There is no difference in which people work

How would a psychologist test the hypothesis that a new stress-reduction program really works? a) try to reject the hypothesis that it does work b) try to accept the hypothesis that is does work c) try to reject the hypothesis that it does not work d) try to accept the hypothesis that is does not work

Try to reject the hypothesis that it does not work

When you have a directional hypothesis, the most conservative way to test it would be to use a(n) a) one tailed test in the predicted direction b) one tailed test in the opposite-of-that-predicted direction c) one tailed test, with the region of rejection in the positive tail d) two-tailed test

Two tailed test

Following his review of a number of large data sets obtained from measures widely used in psychology research, Micceri concluded that most of the distributions a) closely approximated the normal curve b) were skewed to the left due to pronounced ceiling effects c) were much flatter (kurtotic) than the normal curve d) were not normal

Were not normal

If the cutoff Z score on the comparison distribution is 1.64 and the sample Z score is 1.32 on the comparison distribution, the correct decision is to a) fail to reject the null hypothesis b) reject the null hypothesis c) accept the research hypothesis d) reject the research hypothesis

fail to reject the null hypothesis

The biggest complaint about significance tests is that they are a) often misused b) mathematically inconsistent c) based on non-random samples d) difficult to learn

often misused

A major misuse of significance tests is the tendency to a) decide that if a result is not significant, the null hypothesis is shown to be true b) decide that the null hypothesis is false when the results obtained are not significant c) accept the research hypothesis when the results are not significant d) claim that a non-significant result is the same as an unimportant result

Decide that if a result is not significant, the null hypothesis is shown to be true

If the mean score on a stress scale is 5, the standard deviation is 2, and the distribution is normal, what would be the mean value when converted to a Z distribution? a) 0 b) 2 c) 5 d) not enough information to make a determination

0 The mean on a normal distribution always has a Z score of 0

The question below is based on the following scenario. Molly wants to pursue a graduate degree at New University but is unsure whether to specialize in law or medicine. To help her decide, she takes the MCAT and LSAT exams. LSAT: Molly's score = 120; Students at New University: M=150 SD=15 MCAT: Molly's score=52; Students at New University: M=40, SD = 6 Using the percentage approximations for the normal curve, the percentage of people having a lower score than Molly on the LSAT would be a) 2% b) 14% c) 48% d) 98%

2%

If the cutoff Z score on the comparison distribution is a +/- 2.31, a psychologist can reject the null hypothesis if the sample Z score on this distribution is a) - 2.16 b) - 1.41 c) 2.16 d) 2.83

2.83

If the cutoff Z score on the comparison distribution is +/- 1.96, a psychologist CANNOT reject the null hypothesis if the sample Z score on this distribution is a) -2.16 b) -1.41 c) 2.16 d) 2.83

-1.41

A psychologist is most likely to calculate Z scores in order to a) compare scores obtained from two different scales b) compare the skew of two different distributions c) determine how far above or below the median score is d) determine the shape of distribution of scores

Compare scores obtained from two different scales

If the mean score on a creativity test is 20, the standard deviation is 5, and the distribution is normal, the percentage of people who would obtain scores between 15 and 25 is a) 34% b) 14% + 34% = 48% c) 50% d) 34% + 34% = 68%

34% + 34% = 68%

Using a normal curve table, the Z score a person would need to be in the top 4% of his or her class on a particular test is a) 4% - 50% = - 46% which corresponds to a Z score of -1.75 b) 50% - 46% = 4%, which corresponds to a Z score of 0.10 c) 50%-4% = 46%, which corresponds to a Z score of 1.75 d) 34% + 14% - 4% = 44%, which corresponds to a Z score of 1.55 or 1.56

50% - 4% = 46%, which corresponds to a Z score of 1.75

Using a normal curve table, if a person has a music aptitude score of 41, which equals Z score of 1.3, the percentage of people having a higher score is a) 40.32 - 50% = -9.68% b) 50% - 40.32% = 9.68% c) 10% - 40.32% = 59.68% d) 50% + 40.32% = 90.32%

50% - 40.32% = 9.68%

Using the percentage approximations for the normal curve, the percentage of scores between the mean and standard deviation below the mean is a) 14% b) 50% c) 34% d) 14% + 34% = 48%

34%