Stats - Exam 2

c. conduct post hoc tests

Following a significant one-way between-subjects ANOVA in which k > 2, what is the next appropriate step? a. interpret the data; no further tests are required b. both A and B c. conduct post hoc tests d. summarize the data; no further tests are required

d. only one design involves observing the same participants in each group

One difference between a repeated-measures design and a matched-samples design is that ______. a. only one design eliminates between-persons variability b. only one design increases the power to observe an effect c. only one design is a type of related-sample design d. only one design involves observing the same participants in each group

b. ±2.086

State the critical value(s) for a t test using a two-tailed test at a .05 level of significance: t(20). a. ±1.725 b. ±2.086 c. ±2.093 d. ±0.687

b. t statistic

The ______ is an inferential statistic used to determine the number of standard deviations in a t distribution that a sample mean deviates from the mean value or mean difference stated in the null hypothesis. a. standard error b. t statistic c. t distribution d. degrees of freedom

a. critical values

When reporting the results of a one-sample z test using APA format, the ______ does not need to be reported. a. critical values b. p value c. test statistic d. effect size

b. a sampling distribution

A distribution of all sample means or sample variances that could be obtained in samples of a given size from the same population is called ______. a. random sampling b. a sampling distribution c. a conditional procedure d. sampling without replacement

d. estimated

A key difference between a t statistic and a z statistic is that the standard error is ______ to compute a t statistic. a. placed in the numerator b. removed c. replaced d. estimated

b. a one-way between-subjects ANOVA

A professor compared differences in class grades between students in their freshman, sophomore, junior, and senior years of college. If different participants were in each group, then what type of statistical design is appropriate for this study? a. a two-independent-sample t test b. a one-way between-subjects ANOVA c. a two-way between-subjects ANOVA d. both A and B

d. related-samples t test

A professor compares scores on a competency exam among students at two times during a single semester. What type of t test is most appropriate for this study? a. two-independent-sample t test b. one-sample t test c. There is not enough information to answer this question. d. related-samples t test

a. matched-samples design

A researcher asks a sample of brothers and sisters to rate how positive their family environment was during childhood. In this study, the differences in ratings between each brother and sister pair were compared. The type of design described here is called a ______. a. matched-samples design b. both A and B c. repeated-measures design

a. repeated-measures design

A researcher compares the difference in the amount of texting by students in class during the first week and last week of classes. The type of design described here is called a ______. a. repeated-measures design b. matched-samples design c. both A and B

a. 3.55

A researcher computes a one-way within-subjects ANOVA in which k = 3 and n = 10. What is the critical value for this test at a .05 level of significance? a. 3.55 b. 4.41 c. 3.16 d. 5.48

d. There is a 3% likelihood of obtaining the test statistic value, if the null were true.

A researcher computes a test statistic and finds that the p value for this test is .03. What does this result mean? a. There is a 3% likelihood that the researcher's hypothesis is correct. b. The probability of committing a Type II error if we reject the null hypothesis is 3%. c. The probability of committing a Type I error if we retain the null hypothesis is 3%. d. There is a 3% likelihood of obtaining the test statistic value, if the null were true.

b. (3, 84)

A researcher conducts a study in which k = 4 and n = 22 in each group. What are the degrees of freedom for the one-way between-subjects ANOVA? a. (4, 88) b. (3, 84) c. (4, 22) d. (3, 18)

c. ±2.110

A researcher records the level of attention among 18 students during an interactive and lecture portion of a single class. If she computes a related-samples t test at a .05 level of significance (two-tailed test), then what are the critical values for this test? a. ±2.101 b. ±1.740 c. ±2.110 d. ±1.734

c. d = 0.33; medium effect size

A researcher reports that mean ratings of liking for some food are 0.8 ± 2.4 (M ± SD). If the null hypothesis was that the mean equals 0, then what is the effect size for this test using estimated Cohen's d? a. d = 3.00; large effect size b. d = 0.33; small effect size c. d = 0.33; medium effect size d. There is not enough information to answer this question.

b. d = 0.05; small effect size

A researcher reports that the mean time it takes to complete an experimental task is 1.4 ± 8.0 (M ± SD) s. If the null hypothesis was that the mean equals 1.0, then what is the effect size for this test using estimated Cohen's d? a. There is not enough information to answer this question. b. d = 0.05; small effect size c. d = 1.05; large effect size d. d = 0.50; medium effect size

d. 36 and 40

A researcher selects a sample of 100 participants from a population with a mean of 38 and a standard deviation of 20. About 68% of the sample means in this sampling distribution should be between a sample mean of ______. a. 34 and 38 b. 38 and 44 c. 18 and 58 d. 36 and 40

c. a distribution of all sample means or sample variances that could be obtained in samples of a given size from the same population

A sampling distribution of the sample mean or variance is ______. a. a distribution of all scores that could be obtained in samples of a given size from one or more populations b. a distribution of all scores that could be obtained in a population c. a distribution of all sample means or sample variances that could be obtained in samples of a given size from the same population d. a distribution of all measures that could be obtained in a given sample of a given size

d. 2.3

An article states that a sample of 40 participants took 12 ± 2.3 (M ± SEM) s to complete a cognitive assessment. Which value is the standard error of the mean? a. 12 b. The standard error of the mean is not reported in the article. c. 40 d. 2.3

8

"Elementary school children spent significantly more time reading the presence of a teacher than when the teacher was absent, t(7) = 2.804, p < .05 (w^2 = 0.46)." In this related-samples t test, how many participants were observed?a. 8 b. 7 c. 5 d. 6

c. reject the null hypothesis

A researcher assigns 21 adolescents to rate the likability of a person described in a vignette as having one of three personality traits. An equal number of participants are assigned to each group. If Fobt = 4.08 for this study, then what was the decision at a .05 level of significance for a one-way between-subjects ANOVA? a. retain the null hypothesis b. There is not enough information to answer this question. c. reject the null hypothesis

a. two-independent-sample t test

A researcher compares differences in mean health scores between students at two local high schools. Assuming that the population variance is unknown, what type of t test is appropriate for this study? a. two-independent-sample t test b. one-sample t test c. There is not enough information to answer this question.

c. two-independent-sample t test

A researcher conducts a study measuring differences in brain activity among rats placed on either a continuous or intermittent reward schedule. Assuming that the population variance in unknown, what t test is appropriate for this study? a. not enough information b. one-sample t test c. two-independent-sample t test

a. Test 2 is associated with larger degrees of freedom.

A researcher conducts two t tests. Test 1 is a two-tailed test with a smaller sample size at a .05 level of significance. Test 2 is a two-tailed test with a larger sample size at a .05 level of significance. What do you know about the degrees of freedom for each test? a. Test 2 is associated with larger degrees of freedom. b. Each test is associated with the same degrees of freedom. c. It depends; there is not enough information to answer this question. d. Test 1 is associated with larger degrees of freedom.

d. between-groups

A researcher notes that the variability attributed to difference between group means is quite large. Which source of variation is the researcher referring to? a. within-groups b. between-persons c. error d. between-groups

d. to retain the null hypothesis

A researcher obtains z = 1.45 for a one-sample z test. What is the decision for this test at a .05 level of significance? a. It depends on whether the test is one-tailed or two-tailed. b. to reject the null hypothesis c. There is not enough information to make a decision. d. to retain the null hypothesis

b. We expect that the population mean is equal to 23 because the sample mean is an unbiased estimator of the population mean.

A researcher randomly selects a sample of athletes and reports that their average score on a health and fitness scale is 23. Based on the characteristics of the sample mean, what does this say about the mean in the population? a. Nothing; it was just a sample. b. We expect that the population mean is equal to 23 because the sample mean is an unbiased estimator of the population mean. c. There is no way to know without knowing the size of the sample. d. It tells us that the mean in the population is no less than 23.

c. Mean scores shifted 0.88 standard deviations in the population.

A researcher reports that the size of an effect in some population is d = 0.88. Which of the following is an appropriate interpretation for d? a. The effect observed in the population was significant. b. Mean scores were significant by 0.88 points in the sample. c. Mean scores shifted 0.88 standard deviations in the population. d. Mean scores were significant by 0.88 points in the population.

b. between-subjects factor

A type of factor in which different participants are observed in each group, or at each level of the factor, is called ______. a. repeated measures factor b. between-subjects factor c. mixed factor d. within-subjects factor

c. decreases

As sample size increases, the standard error of the mean ______. a. does not change b. can increase or decrease c. decreases d. increases

a. different participants are observed one time in each of two or more groups for one factor

Computing a one-way between-subjects ANOVA is appropriate when ______. a. different participants are observed one time in each of two or more groups for one factor b. the same participants are observed in each of two or more groups for one factor c. the levels of one or more factors are manipulated d. all of these

b. prove that his or her hypothesis is correct

In hypothesis testing, a researcher can never ______. a. compute a test statistic before making a decision b. prove that his or her hypothesis is correct c. make decisions about the null hypothesis d. know the likelihood of obtaining a sample mean if the null hypothesis were true

d. All of these

In terms of characterizing samples, statistical theory was developed using a sampling strategy in which ______. a. the order of selecting participants matters b. the same participant can be selected twice in the same sample c. participants are replaced after being sampled d. all of these

b. central limit theorem

Regardless of the distribution of the population, the sampling distribution of sample means will be approximately normally distributed. What characteristic of the mean explains this? a. unbiased estimator b. central limit theorem c. minimal variance d. none of these

d. persons B, C, and D

Suppose you select a sample of three people from a population of four (A, B, C, D). Which of the following samples is possible using the experimental sampling strategy? a. persons B, A, and B b. persons A, C, and A c. persons A, D, and D d. persons B, C, and D

d. all of these

The t distribution is similar to the z distribution except ______. a. it is associated with greater variability b. it is characterized by "thicker" tails compared with the z distribution c. it is associated with scores being more likely in the tails of the distribution d. all of these

c. If we select a sample at random, then on average we can expect the sample mean to equal the population mean.

What does it mean to say that the sample mean is an unbiased estimator of the population mean? a. The sample means will vary minimally from the population mean. b. The sampling distribution of possible sample means is approximately normally distributed, regardless of the shape of the distribution in the population. c. If we select a sample at random, then on average we can expect the sample mean to equal the population mean. d. all of these

a. The null hypothesis always makes statements about a population parameter.

Which of the following statements regarding the null hypothesis is true? a. The null hypothesis always makes statements about a population parameter. b. A decision in hypothesis testing is made about the alternative hypothesis, not the null hypothesis. c. The null hypothesis is the only hypothesis stated in hypothesis testing. d. all of these