Psych Stat Methods Exam 2

Suppose a poll has been conducted on Americans' favorable attitudes towards 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% B. 53% C. 60% D. 56%

A. 51%

Which of the following is not a step when deciding whether or not a population is being represented? A. Compute the mode. B. Set up the sampling distribution. C. Compute the z-score. D. Compare the z-score to the critical value.

A. Compute the mode.

Suppose you flip a fair coin five times and get a "heads" each time. Your friend insists that your next flip certainly 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." B. Yes, due to the gambler's fallacy. C. No, it probably is impossible to get "tails" with this particular coin. D. While you should get "tails," you're probably more likely to get "heads."

A. No, though the gambler's fallacy makes us think this, it is not a guarantee that the next flip will be "tails."

Which of the following is not true of the criterion? A. Samples meeting the criterion occur more than 5% of the time. B. Sample means occurring with a probability less than that of the criterion probability are likely to represent some other population. C. The criterion is the probability defining samples as unlikely. D. Behavioral researchers usually use 0.05 as their criterion probability.

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

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 mean represents some other population. B. Since the z-value does not fall within the region of rejection, we should conclude this sample mean likely represents some other population. C. Since the z-value falls within the region of rejection, we should conclude this sample mean likely represents some other population. D. Since the z-value falls within the region of rejection, we should not conclude this sample mean represents some other population

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

Which of the following statements does not belong A. The change in the dependent scores was produced by significant sampling error. B. Our condition of the independent variable produced a significant difference in the dependent scores. C. There is a significant effect of the condition. D. We obtained a significant z.

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

What is S-x? A. The estimated standard error of the mean B. The population standard deviation C. The standard error of the mean D. The estimated population standard deviation

A. The estimated standard error of the mean

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. The researcher has made a Type I error. B. The researcher has made a correct decision to reject the alternative hypothesis. C. The researcher has made a correct decision to reject the null hypothesis. D. The researcher has made a Type I error.

A. The researcher has made a Type I error.

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. B. The populations of raw scores form at least a roughly normal distribution. C. There is homogeneity of variance. D. There are two independent samples of interval/ratio scores.

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

When is a one-tailed test used? A. When a relationship is predicted and the direction in which the scores will change is predicted B. When a relationship is predicted without stating the direction in which the scores will change C. When the demonstrated relationship is predicted D. When no relationship is predicted

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

In an experiment, the "proportion of variance accounted for" is also called the A. effect size. B. standard error of the difference between means C. confidence interval. D. error reduction coefficient.

A. effect size.

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-samplest-test. B. one-samplet-test. C. related-samplest-test. D. z-test.

A. independent-samplest-test.

The range of probabilities A. must be between 0 and 1 B. must be at least 0, but it has no higher limit. C. is limitless. D. is between 0 and 100.

A. must be between 0 and 1

When statisticians report results as nonsignificant, the results are A. not too unlikely to accept as representing the same population. B. not due to chance. C. not important. D. different from what was expected or predicted

A. not too unlikely to accept as representing the same population.

The precise location on the dependent measure where we expect our population mean to fall refers to A. point estimation. B. confidence interval. C. interval estimation. D. margin of error.

A. point estimation.

Which of the following is the appropriate statistic for describing the effect size in a two-sample experiment? A. r2pb B. tobt C. tcrit D. Pearsons r2

A. r2pb

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 B. region of criterion value C. critical value D. region of critical value

A. region of rejection

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 the means is A. related-samplest-test. B. independent-samplest-test. C. one-samplet-test. D. z-test.

A. related-samplest-test.

To achieve statistical significance for a one-sample t-test, A. the t-obtained must be larger than the t-critical. B. the t-obtained must be less than the t-critical. C. the t-obtained must equal the t-critical. D. the t-obtained must differ from the -critical by .05.

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

Suppose a researcher assessed attitudes towards a certain brand of soda before and after conducting a taste test and noted the following results: Pre: 5 4 3 5 4 5 Post: 7 9 4 10 4 4 What is the mean difference? A. -12 B. -2 C. 12 D. 6

B. -2

After determining your one-tailed t-test is significant, what should you do? A. See if the test is still significant if you use a two-tailed test. B. Compute a confidence interval for u. C. See if the test is still significant at a higher a. D. See if the test is still significant at a lower a

B. Compute a confidence interval for u.

Which of the following accurately defines a Type I error? A. Failing to reject Ho when it is true B. Failing to reject Ho when it is false C. Rejecting Ho when it is true D. Rejecting H, when it is false

B. Failing to reject Ho when it is false

What does the tobt value indicate? A. The probability of rejecting the null hypothesis B. How far the sample mean is from the u of the sampling distribution of means C. The probability of retaining the null hypothesis D. How far the population mean, u, is from the mean of the sampling distribution of means

B. How far the sample mean is from the u of the sampling distribution of means

What are we stating if we reject the null hypothesis for the independent-samplest-test? A. The difference between the population means is zero B. The sample mean difference represents a difference between two population us that is not zero. C. The sample mean difference represents no difference between two population us. D. The sample mean difference is zero.

B. The sample mean difference represents a difference between two population us that is not zero.

What is the standard error of the difference? A. The pooled standard deviation from the populations from which the samples are drawn B. The standard deviation of the sampling distribution of differences between means C. The standard deviation of the sampling distribution of the mean D. The standard deviation of the sample means

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

When does sampling error occur? A. When a sample statistic is not equal to the population parameter as a result of nonchance factors B. When a sample statistic is not equal to the population parameter as a result of chance factors C. When there has been an error in calculating the sample mean D. When there has been an error in calculating the standard error of the mean

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

Inferential statistics are used to A. decide whether the population causes a particular relationship in the sample data B. decide whether sample data represent a particular relationship in the population C. improve sampling error. D. get rid of sampling error.

B. decide whether sample data represent a particular relationship in the population

For a two-tailed test with a = 0.05, the tcrit value is A. either +1.96 or -1.96. B. different for each df. C. both +1.96 and -1.96. D. either +1.645 or -1.645.

B. different for each df.

When you see the symbol "p," it refers to A. percentile. B. probability. C. population. D. Power.

B. probability.

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. independent; matched-samples B. related; matched-samples C. independent; repeated measures D. related; repeated measures

B. related; matched-samples

An event's relative frequency in the population equals A. 100%. B. the probability of the event. C. the average number of times an event occurs in the population. D. the odds of the event.

B. the probability of the event.

N represents _________ whereas n represents __________. A. the number of pairs in the study; the number of difference scores in the study B. the total number of scores in the study; the number of scores in each sample C. the number of difference scores in the study; the number of pairs in the study D. the number of scores in each sample; the total number of scores in the study

B. the total number of scores in the study; the number of scores in each sample

By convention, the mean of the sampling distribution equals A. -1 B. 1 C. 0 D. the mean of the sample.

C. 0

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. 3 B. 7 C. 0.7 D. 0.3

C. 0.7

Consistent with the basic premise of a representative sample, if a given population consists of 60% women, your sample should have A. whatever composition of men and women that you can find B. no less than 60% women C. 40% men. D. an equal number of men and women.

C. 40% men.

Which of the following tests is considered to be more powerful? A. Which is more powerful depends on the sample size B. Neither; they are both equally statistically powerful C. A one-tailed test D. A two-tailed test

C. A one-tailed test

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. Since the total point value of "7" has the highest probability of any event in the sampling distribution, this is an extremely likely outcome. B. It is impossible for this to happen if the dice are fair. C. Although not impossible, this outcome is so unlikely the fairness of these dice is questionable. D. This is not so unlikely as to make you doubt the fairness of the dice.

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

Which of the following is not one of the steps in a one-sample t-test? A. Create the null hypothesis (Ho) and alternative hypothesis (Ha). B. Create the sampling -distribution and find tcrit in the t-tables. C. Compute o2x D. Compare tobt to tcrit

C. Compute o2x

When is a sample mean likely to represent a particular population mean? A. It depends on our alpha. B. When our t-obtained is greater than the expected value of t. C. It depends on sampling error. D. When we reject the null hypothesis.

C. It depends on sampling error.

What does the independent-samples -test determine? A. It determines how far u1 is trom u2. B. It determines how far -X1 is from -X2. C. It determines the probability of obtaining the observed difference between -X1and -X2, when Ho is true. D. It determines your a level.

C. It determines the probability of obtaining the observed difference between -X1and -X2, when Ho is true.

Which is not an assumption of a z-test? A. We know the true standard deviation of the population. B. We know the mean of the population of raw scores under another condition of the independent variable. C. The dependent variable is perfectly normal and must involve an interval scale. D. We have randomly selected one variable.

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

What is the critical value? A. The outer end of the region of rejection B. The area under the curve in the region of rejection C. The inner edge of the region of rejection D. The absolute value of the entire region of rejection

C. The inner edge of the region of rejection

What happens to the probability of committing a Type I error if the level of significance is changed from a = .01 to a = .05? A. The change in probability will depend on your sample size. B. The probability of committing a Type I error will remain the same. C. The probability of committing a Type I error will increase. D. The probability of committing a Type I error will decrease.

C. The probability of committing a Type I error will increase.

Which of the following requirements is common to both the Z-test and the one-sample t-test? A. The raw score population forms a normal distribution, and the population mean and standard deviation are known B. Alpha is selected to be 0.01. C. There is one random sample of interval or ratio scores. D. The standard deviation of the raw score population is estimated by S x

C. There is one random sample of interval or ratio scores.

When is a -test used instead of a z-test? A. When the population u is known B. When the population standard deviation is known C. When the population standard deviation is unknown D. When the population deals with two samples

C. When the population standard deviation is unknown

What happens to the absolute value of tcrit as df increases? It A. increases B. increases or decreases depending on whether tobt is positive or negative. C. decreases D. remains the same.

C. decreases

The freshmen 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. one-samplet-test. B. z-test. C. independent-samplest-test. D. related-samplest-test.

C. independent-samplest-test.

A nonparametric procedure would not be done in conjunction with A. computing the median B. computing the mode C. ratio distributions D. a skewed intervat distribution

C. ratio distributions

The power of a statistical test is the probability of A. rejecting a true Ho B. failing to reject a true Ho C. rejecting a false Ho. D. failing to reject a false Ho

C. rejecting a false Ho.

Which of the following is one of the requirements of a one-sample t-test? A. The population distribution is skewed. B. The population standard deviation is known C. The obtained scores are either ordinal or interval. D. The population standard deviation is estimated by computing S -x

D. The population standard deviation is estimated by computing S -x

What can you conclude about a sample mean falling within the region of rejection? A. The sample should have come from the given population. B. The sample represents the population on which the sampling distribution was based. C. Another sample needs to be collected. D. The sample probably represents some population other than the one on which the sampling distribution was based.

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

Which of the following is correct regarding statistical hypotheses (null hypothesis and alternative hypothesis)? A. They are the hypotheses we perform on the statistics our experiment. B. We can prove a relationship exists in the population by confirming these hypotheses. C. They describe the sample data if there is or is not a relationship in the population D. They describe the population parameters our sample data represent if there is or is not a predicted relationship

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

Which of the following is correct regarding alternative hypotheses? A. They state the predicted relationship if the sample statistic does not fall in the region of rejection. B. They describe the population parameters represented by the sample data if the predicted relationship does not exist. C. They are alternatives to the experimental hypotheses. D. They describe the population parameters represented by the sample data if the predicted relationship exists.

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

Which of the following is correct regarding experimental hypotheses? A. We can prove a predicted relationship exists in a population by confirming an experimental hypothesis. B. They describe the population parameters to be tested by the experiment. C. We can prove theories about behavior by confirming experimental hypotheses. D. They describe the predicted relationship we may or may not find in an experiment.

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

What is the essence of all inferential statistics? A. Making inferences about the characteristics of samples B. Knowing the characteristics of the population C. Making sure you choose a sample representing the population D. Using sample data to make statements about the scores and relationships in the population

D. Using sample data to make statements about the scores and relationships in the population

Suppose we have a 95% confidence interval of 12.23 and 16.75. What does this mean? A. The average of 12.23 and 16.75 is probably the true population mean. B. We are 95% confident that the true population mean is either 12.23 or 16.75. C. We are at least 95% certain that neither a Type I nor a Type I error was made. D. We are 95% confident that the true population mean is between 12.23 and 16.75.

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

Which of the following is true of any one-sample experiment? A. We must know the sample mean under the condition of the independent variable being tested, but we do not need to know the population mean. B. We must know the population mean under the same condition of the independent variable as the one being tested. C. We must know the sample mean under the condition of the independent variable being tested and under some other condition of the independent variable. D. We must know the population mean under some condition of the independent variable other than the one being tested.

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

An appropriate example of a repeated measures design would be A. ascertaining whether a given sample is a good representative of a given population. B. comparing how men and women differ on memory tasks C. contrasting how the personalities of identical twins may differ. D. comparing individual attitudes about drinking before and after viewing a film on the topic

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

A Cohen's d value of .5 would be viewed as indicative of a _________ effect. A. large B. small C. very large D. medium

D. medium

Which of the following is the correct formula for computing the one-sample t-test? A. t = u - -x/s -x B. t = s -x - u/ -x C. t = -x - u/o -x D. t = -x - u/s -x

D. t = -x - u/s -x