Quiz #11 - Chapters 14 & 15
Which of the following Pearson correlations shows the greatest strength or consistency of relationship?
-0.90
A set of n = 10 pairs of scores has ΣX = 20, ΣY = 30, and ΣXY = 74. What is the value of SP for these data?
14
A researcher would like to test the claim that 9 out of 10 doctors prefer Brand X. A sample of 60 doctors is obtained and each is asked to compare Brand X with another leading brand. The data show that 48 of the doctors picked Brand X. If these data are evaluated using a chi-square test for goodness of fit, what is the expected frequency for Brand X?
54
A chi-square test for independence is being used to evaluate the relationship between two variables, one of which is classified into 3 categories and the second of which is classified into 4 categories. What is the df value for the chi-square statistic?
6
A chi-square test for independence produces a chi-square statistic with df = 2. The data for this research study form a 2×2 matrix with four separate categories.
False
A set of X and Y scores has a Pearson correlation of r = -0.60. For these data, 60% of the variability in the Y scores can be predicted from the relationship with X.
False
For a two-tailed hypothesis test evaluating the significance of a correlation, the null hypothesis states that the sample correlation is zero.
False
The phi-coefficient is used to evaluate effect size for a chi-square test for goodness of fit provided there are only two categories.
False
The results from a research study indicate that adolescents who watch more violent content on television also tend to engage in more violent behavior than their peers. The correlation between amount of TV violence content and amount of violent behavior is an example of _______.
a positive correlation
A chi-square test for independence is being used to evaluate the relationship between two variables. If the test has df = 2, what can you conclude about the two variables?
NOT: One variable consists of 2 categories and the other consists of 4 categories.
A Pearson correlation of r = -0.90 indicates that the data points are clustered close to a line that slopes down to the right.
True
For a regression equation with a slope of b = 3, if MX = 3 and MY = 10, then the Y-intercept for the equation is 1.
True
If other factors are held constant, increasing the sample size for a chi-square test for independence will increase the likelihood of rejecting the null hypothesis.
True
One or two extreme data points can have a dramatic effect on the size of a correlation.
True
The chi-square test for independence is similar to a correlation because it evaluates the relationship between two variables.
True
Which of the following is always true for a chi-square test for goodness of fit or a test for independence?
Both Σfe = n and Σfe = Σfo
What is indicated by a positive value for a correlation?
Increases in X tend to be accompanied by increases in Y
Which correlation should be used to measure the relationship between gender and grade point average for a group of college students?
Point-biserial correlation
What happens to the shape of the chi-square distribution as the df value increases?
The mode (highest point) of the distribution moves to the right.
Under what conditions is Cramér's V used to measure effect size for a chi-square test for independence?
When either of the two variables consists of more than two categories