PSYCH 311 wsu
Rejecting a true null hypothesis is a Type_________________error
1
What are the degrees of freedom for the related samples t test?
A) (nD - 1)
The standard normal distribution is normally distributed with a mean of ____ and a variance of ____.
A) 0; 1
A researcher selects a sample of size 4 from a population of size 6. How many possible samples of this size can be selected using experimental sampling?
A) 15 (4-1 * 6-1)
A researcher selects a sample of 80 people and records the frequency of participants choosing a low, moderate, or high calorie dessert in a buffet. What are the degrees of freedom for this chi-square goodness-of-fit test?
A) 2
A researcher computes a 2 × 2 chi-square test for independence. What is the critical value for this test at a .05 level of significance?
A) 3.84
A researcher reports a significant effect with t(14) = 3.24. Compute eta-squared for this result.
A) = 0.43 (large effect size)
Fill in the missing values for A and B in this frequency distribution table:
A) A = 3.2, B = 13
Is a one-sample t test reported differently for one-tailed and two-tailed tests?
A) No, the same values are reported.
Is a one-sample z test reported differently for one-tailed and two-tailed tests?
A) No, the same values are reported.
Two researchers (A and B) compute a one-sample t test. For both tests, the mean difference between the sample and value stated in the null hypothesis is 5, but the standard error is smaller for Researcher A. Which test is more likely to result in a decision to reject the null hypothesis?
A) Researcher A.
Two researchers (A and B) compute a two-independent sample t test. For both tests, the mean difference between the two groups is 10, but the standard error is smaller for Researcher A. Which test is more likely to result in a decision to reject the null hypothesis?
A) Researcher A.
A researcher conducts a chi-square goodness-of-fit test in which k = 3 and = 4.32. What is the decision for this test at a .05 level of significance?
A) Retain the null hypothesis.
A researcher measures the number of trials it takes two samples of participants to master a new task. In both samples, SS = 240. Sample A consisted of 12 participants and Sample B consisted of 18 participants. Which sample is associated with the largest variance?
A) Sample A
The mean crying time of infants during naptime at a local preschool is 12 minutes. The school implements a new naptime routine in a sample of 25 infants and records an average crying time of 8±4.6 (M±SD) minutes. Test whether this new naptime routine reduced crying time at a .05 level of significance.
A) The new naptime routine significantly reduced crying time, t(24) = -4.35, p < .05.
A researcher reports that the mean difference in response time to an auditory versus a visual cue is 0.83 seconds, with a pooled sample variance equal to 2.45. What is the effect size for this test using estimated Cohen's d
A) d = 0.53; medium effect size
A researcher selects a sample of 16 participants from a population with a variance of 4. What is the standard error of the mean?
A) less than 1 (square root of the variance aka standard dev divided by the sqrt of N)
The following distribution most closely approximates a
A) normal distribution
You read about a study testing whether night shift workers sleep the recommended 8 hours per day. Assuming that the population variance of sleep (per day) is unknown, what type of t test is appropriate for this study
A) one-sample t test
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
A type of related samples design in which participants are observed more than once is called a
A) repeated measures design
The estimated standard error in the t statistic uses the ________ to estimate the ________ when the population variance is unknown.
A) sample variance; population variance
Researchers measure data in a ________ to learn more about individuals in the larger _______ of interest.
A) sample; population
The normal distribution is symmetrical, which means that
A) scores above the mean are distributed the same as scores below the mean
99. As a general rule, the larger the degrees of freedom for a chi-square test,
A) the smaller the critical value will be
The size of a population is symbolized as ________, whereas the size of a sample is symbolized as ________.
A) u; M
How is the standard error of the mean typically reported in a graph?
A) using error bars
Each deviation in the numerator for variance is squared because
A) without squaring each deviation, the solution for SS would be zero
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
B) matched samples design
Which of the following is a type of related samples design in which different participants are actually observed in each group, but treated statistically as if they are the same persons in each group.
B) matched samples design
A correlation coefficient can ______ demonstrate cause.
B) never
The Spearman rank-order correlation coefficient is a measure of the direction and strength of the linear relationship between two ________ variables.
B) ordinal
The probability of a college student being employed is p = .35. The probability of a student being employed and dropping out of college is p = .20. Hence, the probability of a student dropping out of college, given that he or she is employed, is
B) p = .57 (.2/.35)
Regardless of the shape of the distribution in the population, the sampling distribution of sample variances approximates a
B) positively skewed distribution
A chi-square goodness-of-fit test shows that the frequencies observed fit well with those that were expected. Hence, the decision was to
B) retain the null hypothesis
What values are distributed along the x-axis for a sampling distribution of the sample mean?
B) sample means
Correlations can be depicted in a graph called a _______________
B) scatter plot
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.
B) t statistic
Scores far from the mean are located in the ________ of a normal distribution.
B) tails
What is the implication for the tails of a normal distribution being asymptotic?
B) that extreme scores are possible in a normal distribution
44. Each of the following statements are true, except that
B) the larger the sample size, the larger the standard error
Which of the following best describes a dependent variable?
B) the measured behavior
The appropriate correlation coefficient for measuring the direction and strength of the linear relationship between one continuous and one dichotomous variable is
B) the point-biserial correlation coefficient
To compute a related samples t test, a researcher has to know many values. Which of the following is NOT a value that the researcher must know to compute this test?
B) the population variance of difference scores
A researcher records differences in ratings of emotion among participants watching either a drama or a romance film. Assuming that the population variance is unknown, what type of t test is appropriate for this study?
B) two-independent sample t test
The numerator of the correlation coefficient measures the extent to which two variables
B) vary independently
A researcher measures the relationship between narcissism and willingness to help. If = 240, = 320, and = 410, then what is the value of the correlation coefficient?
C) 0.66
The following is a simple frequency distribution table. If we convert this frequency distribution to relative percentages, which of the following gives the corresponding percentages in each interval listed from the top down.
C) 20%, 13%, 17%, 33%, 17%
A researcher selects a sample of 32 participants who are assigned to participate in a study with one group. What are the degrees of freedom for this test?
C) 31
A normal distribution has a mean equal to 53. What is the standard deviation of this normal distribution if 2.5% of the proportion under the curve lies to the right of x = 66.72? (Round your answer to two decimal places)
C) 7.00 (find the z score for 7, or for 66.72)
A researcher computes a 3 × 5 chi-square test for independence. What are the degrees of freedom for this test?
C) 8
If the standard deviation of a probability distribution is 9, then the variance is
C) 81
A researcher records the sound (in decibels) during a series of lessons taught by a substitute teacher at a local elementary school. In his study, he found that the sound was 80±6 (M±SD) decibels. Assuming the data are normally distributed, which of the following is an appropriate conclusion?
C) 95% of classes were between 68 and 92 decibels.
Which of the following measures of effect size can be reported with a 3 × 4 chi-square test for independence?
C) Cramer's V
A researcher records the following data: 4, 4, 4, 4, and 3. How would you describe the variability of these data?
C) It is very small (close to 0) because scores are approximately the same.
Eta-squared is computed ______ for the one-sample, and the two-independent sample t tests.
C) Similarly
A professor grades 120 research papers and reports that the average score was an 80%. What do we know about the sum of the differences of these 120 scores from their mean of 80%?
C) The sum of the differences is equal to zero.
Suppose that a researcher selects a sample of participants from a population. If the shape of the distribution in this population is positively skewed, then what is the shape of the sampling distribution of sample means?
C) approximately normally distributed
Which of the following is a statistical procedure used to test hypotheses about the discrepancy between the observed and expected frequencies in two or more nominal categories?
C) chi-square test
Bayes' theorem is often applied to a variety of ________ probability situations, including those related to statistical inference.
C) conditional
A researcher reports that the mean difference in the body weight of rats following a pharmacological versus control treatment is 14 grams, with a pooled sample variance equal to 256. What is the effect size for this test using estimated Cohen's d?
C) d = 0.88; large effect size
The use of tables and graphs to summarize data is an example of
C) descriptive statistics
Which of the following is the assumption that there is an equal variance of data points dispersed along the regression line?
C) homoscedasticity
One difference between a repeated measures design and a matched samples design is that
C) only one design involves observing the same participants in each group
A cumulative percentage summary that indicates the percentage of scores at or below a given value is called a
C) percentile rank
Each of the following is an example of quantitative data, except
C) political affiliation
A researcher conducts a study in which the population variance of difference scores between two groups is unknown. What type of t test is most appropriate for this study
C) related samples t test
A researcher conducts a study in which the same participants are observed across each level of the independent variable. If there are only two levels of the independent variable, then what type of t test is appropriate for this study?
C) related samples t test
What values are distributed along the x-axis for a sampling distribution of the sample variance?
C) sample variances
For the experimental sampling strategy,
C) sampling is without replacement
A researcher records 17 scores. What is the median position of these scores?
C) the average of the 8th and 9th scores in numeric order
Which of the following best describes an independent variable?
C) the manipulated variable
You are interested in measuring the construct, reinforcement. Which of the following measures for this construct is quantitative and continuous?
C) the size of a reward in grams
The normal distribution has all of the following characteristics, except
C) the total area under the curve is greater than 1.0
When would a researcher calculate a population mean?
C) when data are measured for all members of a population
State the critical value(s) for a t test using a two-tailed test at a .05 level of significance: t(20).
C) ±2.086
The probability of making zero to two errors per 1,000 keystrokes is 0.43, and the probability of making three to five errors per 1,000 keystrokes is 0.28. Find the probability (per 1,000 keystrokes) associated with making at most five errors.
D) .71 (.43 + .28)
Which measure of effect size is most commonly reported with a t test?
D) Cohen's d
A chi-square goodness-of-fit test leads to a decision to retain the null hypothesis. Which of the following correctly explains this decision?
D) Frequencies observed were statistically similar to the frequencies expected at each level of the categorical variable
Computing a one-sample t test is appropriate when
D) all of the above
Computing a two-independent sample t test is appropriate when
D) all of the above
For the related samples t test, assuming that all other values remain constant, then as samples size increases,
D) all of the above
The assumptions for performing Pearson r test are
D) all of the above
The t distribution is similar to the z distribution except
D) all of the above
Which of the following is an assumption for computing any type of independent sample t test?
D) all of the above
Which of the following is an example of a parametric test?
D) all of the above
If the expected frequencies equal to observed frequencies for a chi-square test for independence, what do we conclude?
D) both B and C
Which of the following is recorded using a chi-square goodness-of-fit test and a chi-square test for independence?
D) both B and C
When the probability of one outcome changes depending on the occurrence of a second outcome, these outcomes are referred to as
D) conditional
When reporting the results of a one-sample z test using APA format, the ________ does not need to be reported.
D) critical values
Many nonparametric tests are called ________ because they make no assumptions regarding the shape of the distribution in the population.
D) distribution-free tests
When computing a chi-square goodness-of-fit test, the frequency expected in a given cell should never be less than
D) five
A therapist observes that spouses are more likely to forgive their partners for lying to them if they find out the truth from their spouse and not a third party. In this example, the dependent variable is
D) forgiveness
Each of the following is an advantage for using the related samples design, except
D) it increases the variability measured in a study
A researcher conducts two chi-square tests. The 2 × 2 chi-square was 2 = 3.82. The 2 × 3 chi-square was 2 = 5.02. Which chi-square test resulted in a decision to reject the null hypothesis at a .05 level of significance?
D) none; both chi-square tests result in a decision to retain the null hypothesis
The Friedman test is used as a nonparametric alternative to which parametric test?
D) one-way within-subjects ANOVA
The denominator of the test statistic for a related samples t test
D) provides an estimate of the error associated with the difference scores
The correlation coefficient is used to measure the ________ and ________ of the linear relationship between two factors.
D) strength; direction
Which of the following summarizes a t test that was significant and associated with a large effect size?
D) t(12) = 2.95, p < .05, d = .82
The unit of measurement distributed along the x-axis of a standard normal distribution is referred to as a
D) z score
A researcher matched 30 participants on intelligence (hence 15 pairs of participants), and then compared differences in emotional responsiveness to two experimental stimuli between each pair. For this test, what are the critical values, assuming a two-tailed test at a .05 level of significance?
D) ±2.145
Give the names for two commonly used measures of effect size for t tests that give you the proportion of variance explained in the DV
Eta squared
The sample variance is:
an unbiased estimator of the population variance associated with n - 1 degrees of freedom computed by dividing SS by df D) all of the above
As ________________ increases, the power to detect an effect increases.
sample size
What is the z score for scores in the bottom 5%?
B) -1.645
Measures of variability can range in value from
B) 0 to +
A researcher reports the following results for a chi-square test: (1) = 5.386, p < .05 (V = 0.224). If this test were a test for independence, then how many groups (cells) were observed?
B) 2
A researcher finds that 12% of participants make between 3-5 visits to a physician each year. What are the real limits for this interval?
B) 2.5-5.5
A researcher wants to know the probability of being named on the honor roll from a population where 8% of students are on the honor roll. If the researcher selects a sample of 400 students, then what is the mean number of students expected to be on the honor roll? Hint: This is a binomial distribution, where p = 0.08 and q = 0.92.
B) 32 (400 * .08)
A researcher determines that the probability of missing class among students at a local school is p = .16. Assuming that the school has 300 students enrolled, how many students can we expect to miss class on a given day? Hint: This is a binomial probability distribution.
B) 48 students (300 * .16 n*p)
A researcher computes a 2 × 3 chi-square test for independence. What is the critical value for this test at a .05 level of significance?
B) 5.99
A researcher records the frequency of participants selecting one of four new slogans for an advertising campaign. If it was expected that among 200 people polled there would be no preference for any one slogan, then what was the expected frequency for each slogan.
B) 50 people
A researcher conducts a study, but has low power to detect an effect. Which of the following is one way in which the research can increase power?
B) Increase the sample size.
A researcher measures the following correlation between cost of produce and number of units sold. Which description best explains the relationship between these two factors?
B) Less expensive produce is associated with an increased number of units sold.
A researcher measures the amount of coffee consumed by college students while studying during the final exam week. In her study, she found that students drink 2.3±0.8 (M±SD) cups of coffee per study session. Assuming the data are normally distributed, which of the following is the most appropriate conclusion?
B) Most students drink between 1.5 and 3.1 cups of coffee per study session.
A researcher has participants rate the likability of a sexually promiscuous person described in a vignette as being male (n = 20) or female (n = 12). The mean likability ratings in each group were 4.0. If the null hypothesis is that there is no difference in likability ratings, then do likability ratings differ at a .05 level of significance?
B) No, this result is not significant, t(30) = 0.
A researcher measures deviant behavior in a sample of 12 children from abusive homes (Sample A). Another researcher measures the same behavior in a sample of 18 children from abusive homes (Sample B). Which sample is associated with larger degrees of freedom?
B) Sample B
What is the description of SS (Sum of squares) in words? That is, what does it stand for?
B) Sum of squared deviations of scores from the mean.
A researcher conducts two t tests. Test 1 is a one-tailed test with a smaller sample size at a .05 level of significance. Test 2 is a one-tailed test with a larger sample size at a .05 level of significance. What do you know about the critical values for each test?
B) Test 2 is associated with smaller critical values.
All other things being equal, as the sample size increases, what happens to the critical value for a related samples t test (or for any t test, for that matter)?
B) The critical value decreases.
Which proportion is largest in a z distribution?
B) The proportion of area between z = +1 and z = -1.
Which of the following is a key assumption for a chi-square goodness-of-fit test?
B) The variance between groups is equal.
The degrees of freedom for the sample variance
B) are equal to the sample size minus one
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?
B) d = 0.33; medium effect size
The test statistic for a related samples t test makes tests concerning a single sample of A)
B) difference scores
In the stem-and-leaf display, each number to the right of the vertical line is referred to as a ________; the numbers to the left of the vertical line are called the ________.
B) leaf; stem
The assumption that there is an equal variance or scatter of data points dispersed along the regression line is referred to as
B) linearity
