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Statistical Methods of Psychology > Exam 2 Review Q's > Flashcards

Exam 2 Review Q's Flashcards

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1
Q

A scatter plot ____________.

A

is a graph of paired X and Y values

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2
Q

An event’s relative frequency in the population equals

A

the probability of an event.

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3
Q

When rolling a pair of fair dice, the probability of rolling a total point value of “7” is 0.17. If you rolled a pair of dice 1,000 times and the point value of “7” appeared 723 times, what would you probably conclude?

A

Although not impossible, this outcome is so unlikely the fairness of these dice is questionable.

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4
Q

What do we call the portion of the sampling distribution in which values are considered too unlikely to have occurred by chance?

A

Region of rejection

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5
Q

What is the critical value?

A

The inner edge of the region of rejection

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6
Q

Which of the following is NOT true of the criterion?

A

Samples meeting the criterion occur more than 5% of the time.

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7
Q

What can you conclude about a sample mean falling within the region of rejection?

A

The sample probably represents some population other than the one on which the sampling distribution was based.

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8
Q

Which of the following is not a step when deciding whether or not a population is being represented?

A

Compute the mode.

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9
Q

A study about the college aptitude of seniors at South City High School has resulted in a sample mean with a corresponding z-score of +1.89. If the critical value for the region of rejection is +1.96, what is the correct conclusion?

A

Since the z-value does not fall within the region of rejection, we should not conclude this sample man represents some other population.

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10
Q

When does sampling error occur?

A

When a sample statistic is not equal to the population parameter as a result of chance factors.

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11
Q

When you see the symbol “p”, it refers to

A

probability

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12
Q

Suppose you flip a fair coin five times and get a “heads” each time. Your friend insists that your next flip will come up as tails. Is your friend correct?

A

No, though the gambler’s fallacy makes us think this, it is not a guarantee that the next flip will be “tails.”

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13
Q

Consistent with the basic premise of a representative sample, if a given population consists of 60% women, your sample should have

A

40% men.

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14
Q

The range of probabilities

A

must be between 0 and 1.

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15
Q

Suzy is about to pick a cookie from a cookie jar. The cookie jar contains 4 chocolate chip, 3 vanilla, 2 ginger snap, and 1 sugar cookie. What is the probability that Suzy will not pick a vanilla cookie?

A

7/10 chance, so 0.7.

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16
Q

Inferential statistics are used to

A

decide whether a sample data represents a particular relationship in the population.

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17
Q

Which of the following is correct regarding experimental hypotheses?

A

They describe the predicted relationship we may or may not find in an experiment.

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18
Q

When is a one-tailed test used/

A

When a relationship is predicted and the direction in which the scores will change is predicted.

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19
Q

Which of the following is correct regarding statistical hypotheses (null and alternative hypothesis?)

A

They describe the population parameters our sample data represent if there is not a predicted relationship.

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20
Q

Which of the following is true of any one-sample experiment?

A

We must know the population mean under some condition of the independent variable other than the one being tested.

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21
Q

Which of the following is correct regarding alternative hypotheses?

A

They describe the population parameters represented by the sample data if the predicted relationship occurs.

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22
Q

Which of the following statements does not belong?

A

The change in the dependent scores was produced by significant sampling error.

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23
Q

When statisticians report results as nonsignificant, the results are

A

not too unlikely to accept as representing the same population.

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24
Q

Which of the following accurately defines a Type II error?

A

Failing to reject Ho, when it IS false.

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25
Q

Which of the following tests is considered to be more powerful?

A

A one-tailed test.

26
Q

A nonparametric procedure would not be done in conjunction with

A

ratio distributions

27
Q

Which is not an assumption of a z-test?

A

The dependent variable is perfectly normal and must involve an interval scale.

28
Q

Suppose a researcher has made a decision that a certain pill is not effective at treating depression when, in reality, it is. What has the researcher done in this case?

A

This researcher has made a type II error.

29
Q

What happens to the probability of committing a Type I error if the level of significance is changed from alpha = 0.01 to alpha - 0.05?

A

The probability of committing a Type I error will increase.

30
Q

The POWER of a statistical test is the probability of

A

rejecting a false Ho.

31
Q

When is a t-test used instead of a z-test?

A

When the population standard deviation is unknown.

32
Q

What is the Sx bar?

A

The estimated standard error of the mean

33
Q

Which of the following is one of the requirements of a one-sample t-test?

A

The population standard deviation is estimated by computing Sx.

34
Q

What does Tobt value indicate?

A

How far the sample mean is from the mu of the sampling distribution.

35
Q

Which of the following requirements is common to both the z-test and the one-sample t-test?

A

There is one random sample of interval or ratio scores.

36
Q

Which of the following is NOT one of the steps in a one-sample t-test?

A

Compute O2x (variance)

37
Q

Which of the following is the correct formula for computing the one-sample t-test?

A

t = x bar - mu / Sx bar

38
Q

For a two-tailed test with an alpha of 0.05, the Tcritical value is

A

different for each df.

39
Q

What happens to the absolute value of Tcritical as df increases? It ____

A

decreases.

40
Q

After determining your one-tailed t-test is significant, what should you do?

A

Compute a confidence interval for mu.

41
Q

The precise location of the dependent measure where we expect our population mean to fall refers to

A

point estimation

42
Q

Suppose a poll has been conducted on Americans’ favorable attitudes toward a certain issue. If it is reported that Americans are 56% +- 4% in favor of the issue, which of the following is NOT a possible value represented within the margin of error?

A

51%

43
Q

To achieve statistical significance for a one-sample t-test,

A

the t-obtained must be larger than the t-critical.

44
Q

When is a sample mean likely to represent a particular population mean?

A

It depends on the sampling error.

45
Q

Suppose we have a 95% confidence interval of 12.23 and 16.75. What does this mean?

A

We are 95% confident that the true population mean is between 12.23 and 16.75

46
Q

The first 10 students who arrived for the Friday lecture filled out a questionnaire on their attitudes toward the instructor. The first 10 who were late for the lecture were spotted and afterward filled out the same questionnaire. The appropriate design for testing the significance of the difference between the means is ______

A

independent- samples t-test.

47
Q

the freshman competed with the sophomores to see who could raise the most money by recycling. The appropriate design for testing the significance of the difference between the means is

A

independent-samples t-test.

48
Q

Which of the following is not one of the assumptions of the t-test for independent samples?

A

The standard deviation of at least one of the populations is known.

49
Q

N represents _____, whereas n represents _______.

A

the total number of scores in the study, the number of scores in each sample.

50
Q

What does the independent-samples t-test determine?

A

It determines the probability of obtaining the observed difference between Xbar1 and Xbar 2 when Ho is true.

51
Q

What is the standard error of the difference?

A

The standard deviation of the sampling distribution of differences between means.

52
Q

What are we stating if we reject the null hypothesis for the independent-samples t-test?

A

The sample mean difference represents a difference between two populations mus that is not zero.

53
Q

In a study involving stress among college students, a group of seniors are asked to complete a stress survey. After a two-hour seminar on relaxation methods, they are asked to complete the stress survey again. The appropriate design for testing the significance of the difference between means is

A

related samples t-test.

54
Q

Which of the following is the appropriate statistic for describing the effect size in a two-sample experiment?

A

rpb^2

55
Q

In an experiment, “the proportion of variance accounted for” is called the

A

effect size

56
Q

By convention, the mean of the sampling distribution equals

A

0

57
Q

Suppose a researcher compares 50 pairs of husbands and wives on a variety of attitudes. In doing so, the researcher is making use of ______ samples with a _______ design.

A

related; matched-samples

58
Q

Suppose a researcher assessed attitudes towards a certain brand of soda before and after conducting a taste test and noted the following:
(table pre and post). What is the mean difference?

A

-2

59
Q

An appropriate example of a repeated measures design would be

A

comparing individual attitudes about drinking before and after viewing a film on the topic.

60
Q

A Cohen’s d value of 0.5 would be viewed as indicative of a ______ effect.

A

medium

Statistical Methods of Psychology (1 decks)

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