PSY-10 Final
A researcher compares differences in positivity between participants in a low-, middle-, or upper middle-class family. If she observes 15 participants in each group, then what are the degrees of freedom for the one-way between-subjects ANOVA?
(2, 42)
If SSXY = -16.32 and SSX = 40.00 for a set of data points, then what is the value of the slope for the best-fitting linear equation?
-0.41
A researcher reports the following equation for a best-fitting straight line to a set of data points: Y'= -3.24 + 1.01X. Which value is the intercept?
-3.24
The t distribution is similar to the z distribution except ______.
-it is associated with scores being more likely in the tails of the distribution. - it is characterized by "thicker" tails compared with the z distribution. -it is associated with greater variability. - all of these
A researcher measures the relationship between narcissism and willingness to help. If SSXY = 240, SSX = 320, and SSY = 410, then what is the value of the correlation coefficient?
.66
For the linear equation Y' = - 3 + 2X, which of the following points will NOT be on the line?
0, 3
A researcher reports the following equation for a best-fitting straight line to a set of data points: Y' = 12.03 + 0.48X. Which value is the slope?
0.48
For a sample of n = 16 individuals, how large a Pearson correlation is necessary to be statistically significant for a two-tailed test with α = .05?
0.497
For a research study with two levels of factor A, three levels of factor B, and n = 5 in each treatment condition, what are the df values for the F-ratio evaluating the main effect for factor A?
1, 24
On average, what value is expected for the F-ratio if the null hypothesis is true?
1.00
An analysis of variance produces SSbetween = 30, SSwithin = 60, and an F-ratio with df = 2 and 15. For this analysis, what is the F-ratio?
15/4 = 3.75
Suppose that the correlation between height and weight for adults is +0.40. What proportion (or percent) of the variability in weight can be explained by the relationship with height?
16%
An independent-samples study with n = 6 in each of the two samples, produces a sample mean difference of 4 points and a pooled variance of 12. What is the value for the t statistic?
2
For the linear equation Y' = 4 + 2X, if X increases by 1 point, how much will Y increase?
2 points
What is the pooled variance for the following two independent samples? Sample 1: n = 8 and SS = 168 Sample 2: n = 6 and SS = 120
24
A researcher computes a 2 × 4 between-subjects ANOVA. What are the degrees of freedom for Factor B for this study?
3
An analysis of variance produces SSbetween = 40 and MSbetween = 20. In this analysis, how many groups are being compared?
3
A two- way study with two levels of factor A and three levels of factor B uses a separate group of n = 5 participants in each treatment condition. How many participants are needed for the entire study?
30
A set of n = 15 pairs of X and Y scores has SSX = 10, SSY = 40, and SSxy = 30. What is the slope for the regression equation for predicting Y from X?
30/10
If b = -0.57, Y-bar = 2.75, and X-bar = 5.25 for a set of data points, then what is the value of the intercept for the best-fitting linear equation?
5.74
In a sample of 20 participants, a researcher estimates the 95% CI for a sample with a mean of 5.4 and an estimated standard error of 1.6. What is the upper confidence limit for this interval?
8.8
In a sample of 28 participants, a researcher estimates the 95% CI for a sample with a mean of 1.5 and an estimated standard error of 0.3. What is the confidence interval at this level of confidence?
95% CI (0.9, 2.1)
A researcher measures the following correlation between cost of produce and number of units sold. Which description best explains the relationship between these two variables?
Less expensive produce is associated with an increased number of units sold.
Which of the following not used in an F ratio for the two-way ANOVA?
MS between
A researcher conducts a related-sample study to evaluate two treatments with n = 16 participants and obtains a t statistic of t = 1.94. The treatment 2 is expected to have a greater sample mean than the treatment 1. What is the correct decision for a hypothesis test using α = .05?
Reject the null hypothesis with a one-tailed test but fail to reject with two tails.
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?
Test 2 is associated with larger degrees of freedom.
For the regression equation, Y' = 6 -2X, what can be determined about the correlation between X and Y?
The correlation definitely will be negative.
The mean crying time of infants during naptime at a local preschool is 12 mins. The school implements a new naptime routine in a sample of 25 infants and records an average crying time of 8 mins (SD=4.6). Test whether this new naptime routine reduced crying time at a .05 level of significance.
The new naptime routine significantly reduced crying time, t(24) = -4.35, p < .05.
For a two-tailed hypothesis test evaluating a Pearson correlation, what is stated by the null hypothesis?
The population correlation is zero.
If a two-way ANOVA produces a statistically significant interaction between the two factors A and B, then what can you conclude about the main effects for A and B?
The significance of the main effects is not related to the significance of the interaction.
What is stated by the null hypothesis (H0) for an ANOVA?
There are no differences between any of the population means.
When comparing more than two group means, should you use an analysis of variance rather than using several t tests, and if so, why?
Yes. Using several t tests increases the risk of a Type I error.
In a line graph showing the results from a two-way design, the levels of factor B are presented on the X-axis and separate lines are used to display the means for A1 and A2. If the points on the line for A1 are consistently five points higher than the corresponding point on the line for A2, what pattern of results is indicated?
an indication of an A-effect but no indication of an interaction.
The test statistic for a related-samples t test makes tests concerning a single sample of ______.
difference scores.
In a two-way ANOVA a main effect is defined as the ____.
mean differences among the levels of one factor.
The numerical value for a correlation can ____.
never be greater than 1.00 and can never be less than -1.00
What would the scatterplot show for data that produce a correlation of +0.88?
points clustered close to a line that slopes up to the right.
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 violent content and amount of violent behavior is an example of a ____.
positive correlation
Which of the following indicates the strongest correlation?
r = -0.90
A set of n = 5 pairs of X and Y values has SSX = 16, SSY = 4 and SSxy = 2. For these data, the Pearson correlation is ____.
r = 2/8
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?
related-samples t test.
The difference between your actual value and predicted value in a least squares regression is _______
residual
Two variables are said to interact when ____.
the effect of one independent variable depends on the levels of the second variable.
For an analysis of variance, the term "two-way" refers to ______.
the number of factors in the design.
A significant slope means that ________
the slope is not equal to 0 in the population.
The source of variability associated with error variance in the one-way between-subjects ANOVA is called ______.
within-groups variability.
State the critical value(s) for a t test using a two-tailed test at a .05 level of significance: t(20).
±2.086