Psych 311 Exam 4 Study Guide
If r = .25, then the coefficient of determination is = ___________ 06. (.0625 w/o rounding)
.06
A 2 x 2 chi-square test for independence has ____ degrees of freedom.
1
A researcher computes a 4.6 chi-square for independence with a sample of 120 participants, with ^2 = 14.79. What is the effect size for this result?
B) 0.20
A researcher selects a sample of 110 participants and computes the following phi correlation coefficient: r = 0.31. What is the value of ^2?
B) 10.57
A researcher computes a 2 x 4 chi-square test for independence. What are the degrees of freedom for this test?
B) 3
A researcher computes a 2 x 3 chi-square test for independence. What is the critical value for this test at a .05 level of significance?
B) 5.99
The correlation coefficient ranges from -0.1 to + 1.0, with values closer to +/- 1.0 indicating
B) A stronger relationship between two factors
The Spearman rank-order correlation coefficient is a measure of the diretion and strength of the linear relationship between two ________ variables.
B) Ordinal
We compute the frequency expected in each category. Using known ___________ stated in the null hypothesis.
B) Proportions
A researcher measure the correlation between gender and student aptitude scores from 0 to 100 among 20 participants. If r ^pb=0.49, then what is the decision for this correlation test?
B) Reject the null hypothesis
Suppose a correlation is computed in each of two samples. If the value of SS^xy is the same in each sample, and *sqr. rt. SSx SSy is larger in sample 1, then in which sample will the value of the correlation coefficient be larger?
B) Sample 2
If the expected frequencies equal to observed frequencies for a chi-square test for independence, what do we include?
B) The test statistic value is equal to 0
The denominator of the correlation coefficient measures the extent to which two variables
B) Vary independently
One way a researcher can correct for having expected frequencies smaller than five is to increase the levels of the categorical variable such that the number of levels
B) is greater than four
What is the key assumption for a chi-square goodness-of-fit test?
B) observed frequencies are independently recorded in each cell
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
The most common measure of effect size for the correlation coefficient is called
B) the coefficient of determination
As a general rule, the larger the degrees of freedom for a chi-square test,
B) the larger the critical value will be
The Mann-Whitney U test is used as a nonparametric alternative to which parametric test?
B) two-independent sample t-test
The degrees of freedom for independence test are
C) (K^1-1) (K^2-1) (^ means subscript for this one)
The correlation coefficient ranges between __________ and _________.
C) -1; +1
A researcher measures the following correlation between number of years of education and life satisfaction: r= + 0.08. What is the value of the coefficient of determination?
C) 0.01
A researcher measures the relationship between two variables, x and y. If SS^xy = 340 and SSx SSy = 320,000, then what is the value of the correlation coefficient?
C) 0.60
A researcher measures the relationship between narcissism and willingness to help. If SS^xy = 240, SSx = 320, and SSy = 410, then what is the value of the correlation coefficient?
C) 0.66
An unanticipated variable not accounted for in a research study that could be causing or associated with observed changes in one or more measured variables is called
C) A confound variable
The assumption that there is an equal variance or scatter of data points dispersed along the regression line is referred to as
C) Homoscedasticity
Which of the following indicates the strongest correlation?
C) r = 0.90
The Wilcoxon signed-ranks T test is used as a nonparametric alternative to which parametric test?
C) related samples t-test
Which of the following would NOT be reported for a correlation?
C) the critical values for each test
The appropriate correlation coefficient for measuring for the direction and strength of the linear relationship between two dichotomous variables is
C) the phi correlation
To compute the expected frequencies for a chi-square test for independence, we use which of the following formulas?
D) (row total x column total)/ grand total
Which of the following is an appropriate measure of effect size for a 2 x 2 chi-square test for independence?
D) All of the above
Which of the following is an example of a parametric test?
D) All of the above
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 researcher conducts two chi-square tests. The 2 x 2 chi-square was x^2 = 3.82. The 2 x 3 chi-square was x = 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 resulting a decision to retain the null hypothesis
The correlation coefficient is used to measure the _______ and _________ of the linear relationship between two factors.
D) Strength; direction
Outliers can change the ______________ of a correlation
D) all of the above
Select the description below that identifies the following correlation: r= .28, p > .01.
D) all of the above
To summarize correlations, we report:
D) all of the above
The sign test is used as a nonparametric alternative to which parametric test?
D) both A and C
The numerator of the correlation coefficient measure the extent to which two variables
D) both A and C (vary together; covary)
The Friedman test is used as a nonparametric alternative to which parametric test?
D) one-way within-subjects ANOVA
The sign (+ or -) of a correlation coefficient indicates the ____________ of a relationship between two factors
Direction
When at least one categorical variable has more than two levels, Cramer's V is used to estimate _________________ for a chi-square test for independence.
Effect size
The formula for the chi-square test measures the size of the discrepancy between observed and _____________ frequencies
Expected
In a chi-square test, one assumption that must be met concerns the expected frequencies for any given cell. What is this assumption?
It must be at least 5
When finding the critical value in a chi-square distribution, how many tails do you look for in the cutoff?
One tail
The Spearman correlation coefficient is used to measure the correlation between two variables that are measured on a(n) _______________ scale.
Ordinal
To summarize the chi-square for independence, report the test statistic, degrees of freedom, observed. Frequencies (or percentages), effect size, and the ______________ value.
P
When the chi-square test for independence is significant, this indicates that two variables are ______________________.
Related (or dependent or correlated)
The formula for the Spearman correlation coefficient was derived from the formula for
The Pearson correlation coefficient (or just "Pearson r")
Name the correlation coefficient used to test the relationship between these four sets of variables (so, state the four answers, in order:)
1. height and weight (Pearson r) 2. retirement status (yes or no)+ blood pressure (point biserial) 3. retirement status + death... (phi) 4. Rankings of runners on place (Spearman)
A researcher measures the following correlation: r= - 0.21. What is the value of the coefficient of determination?
A) 0.04
If ^2=5.32 and n=40, then what is the value of the coefficient of determination?
A) 0.133
The degrees of freedom for a chi-square goodness-of-fit test are
A) K-1
What is a key distinction between parametric tests and nonparametric tests in terms of scales of measurement?
A) Parametric tests are used for interval and ratio data, whereas nonparametric tests are used for nominal and ordinal data
A researcher computes the following phi correlation coefficient: r=0.42. If the sample size was 20, then what is the decision for this correlation test?
A) Retain the null hypothesis
A researcher conducts a chi-square goodness-of-fit test in which k = 3 and ^2 = 4.32. What is the decision for this test at a .05 level of significance?
A) Retain the null hypothesis
The appropriate correlation coefficient for measuring the direction and strength of the linear relationship between two ranked or ordinal variables is
A) The Spearman correlation coefficient
A correlation of r = .38 in a sample of 30 participants is statistically significant for a two-tailed test at a .05 level of significance
A) True
The coefficient of determination is mathematically equivalent to eta- squared.
A) True
The point-biserial correlation coefficient is a measure of the direction and strength of the linear relationship between two variables, where
A) one is continuous, and one is dichotomous
One way a researcher can correct for having expected frequencies smaller than five is to increase the sample size such that
C) It is five times larger than the number of cells
A researcher computes a 4 x 4 chi-square test for independence and estimates the following effect size: v = 0.36. This effect size is
C) Large
A researcher measures the correlation between self-esteem (high, low) and physical fitness scores among school athletes. In the study, 12 participants reported high self-esteem and 12 reported low self-esteem. If S^y=9.06 and M^y2=11, then what is the value of the correlation coefficient?
A) 0.61
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 determines that ^2=3.76 to test for significance for a phi correlation test?
A) Retain the null hypothesis
A researcher conducts two chi-square tests. The 2 x 2 chi-square was x^2 = 3.92. The 2 x 3 chi-square was x^2 = 5.92. Which chi-square test resulted in a decision to reject the null hypothesis at a .05 level of significance?
A) The 2 x 2 chi-square
Which of the following is the assumption that there is an equal variance of data points dispersed along the regression line?
C) Homoscedasticity
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
When the chi-square test for independence is significant, this indicates that there is significant variability between groups.
B) False
A researcher measures the correlation of the time it takes participants to complete two tasks purported to measure the same cognitive skill. Participant times are converted to ranks from fastest to slowest. If D=165 and n=20, then what is the decision for this correlation test?
B) Reject the null hypothesis
A researcher observes a correlation of values from 2 to 10 points and draws conclusions about the full range of values in the population from 0 to 21 points. Which limitation for correctly interpreting a correlation coefficient did the researcher violate?
B) Restriction of range
Which of the following is a statistical procedure use to test hypotheses about the discrepancy between the observed and expected frequencies in two or more nominal categories?
C) Chi-square test
Which of the following is an example of a nonparametric test?
C) Chi-square tests
Which of the following measures of effect size can be reported with a 3 x 4 chi-square test for independence?
C) Cramer's V
A researcher measures the correlation in rankings for a sample of restaurants and consumers' rankings of their favorite restaurants. If D^2= 96 and n=12, then what is the value of the correlation coefficient?
C) O.66
The Kruskal-Wallis H test is used as a nonparametric alternative to which parametric test?
C) One-way between-subjects ANOVA
We convert r to a t statistic for which of the following correlation tests?
C) Point-biserial
A statistical procedure used to describe the strength and direction of the linear relationship between two factors is called
C) a correlation
A researcher reports the following results for a chi-square test: x^2 (1) = 5.386, p < .05 (v = 0.224). if this test were a test for independence, then how many groups were observed?
D) 4
A researcher compares the frequency of participants who sleep primarily on their stomach, back, or side during the night. What is the critical value for a chi-square goodness-of-fit test at a .05 level of significance?
D) 5.99
The normality assumption states that the population of x and y scores form d bivariate ("two variable") normal distribution, such that
D) All of the above
The observed frequencies can be summarized,
D) All of the above
To summarize the chi-square goodness-of-fit test, which of the following is reported?
D) All of the above
Which of the following is a limitation for interpreting a correlation?
D) All of the above
A researcher can correct for having expected frequencies smaller than five by
D) Both A and B (increasing the # of cells; increasing the sample size)
A chi-square goodness-of-fit 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
Which of the following is the assumption that the best way to describe the pattern of data is using a straight line?
D) Linearity
A major weakness in using a nonparametric test like chi-square when a parametric test could validly be used is that the nonparametric test is lower on _________________.
Power
