Data Analysis Exam Final
-1.711
State the critical value(s) for a t test using a .05 level of significance in the lower tail only: t(24)
Sample 2
Suppose a correlation is computed in each of two samples. If the value of SSXY is the same in each sample, and mc014-1.jpg is larger in Sample 1, then in which sample will the value of the correlation coefficient be larger?
Less
The larger the level of confidence, the ______ precise the interval estimate.
True
The least certain, but most precise, estimate is a point estimate.
2.1
In a sample of 20 participants, a researcher estimates the 95% CI for a sample with a mean of M = 5.4 and an estimated standard error (SM) of 1.6. What is the lower confidence limit for this interval?
False
In an analysis of regression there are three sources of variation: regression, residual, and error.
True
Including two or more predictor variables into a single equation of a regression line can be more informative than an analysis using only one predictor variable.
The phi correlation coefficient
The appropriate correlation coefficient for measuring for the direction and strength of the linear relationship between two dichotomous variables is ______.
The point-biserial correlation coefficient
The appropriate correlation coefficient for measuring the direction and strength of the linear relationship between one continuous and one dichotomous variable is ______.
z test
The confidence interval for one sample selected from a population with a known variance is computed using a critical value for which type of test?
All of these
The confidence interval for samples selected from one or two populations with an unknown variance is computed using critical values from the t table. This is true for which of the following types of samples?
Related to changes
The correlation coefficient measures the extent to which changes in one factor are ______ in a second factor.
True
The equation for a straight line is Y = bX + a.
Never
A correlation coefficient can ______ demonstrate cause.
False
A point estimate is associated with a high level of confidence that the estimate is in fact equal to the population mean.
False
A positive correlation is always stronger than a negative correlation.
X significantly predicts Y
A researcher computes the following analysis of regression table. Based on the data given, what is the decision for this test at a .05 level of significance? (Note: Complete the table first.) Source of Variation SS df MS F Regression 1 28 Residual Total 118 19
Retain the null hypothesis
A researcher determines that χ2 = 3.56 to test for significance for a phi correlation coefficient. What was the decision for this phi correlation test?
90%: CI 5.5, 12.4
A researcher estimates the 90% CI for a sample with a mean of M = 8.9 and a standard error (σM) of 2.1. What is the confidence interval at this level of confidence?
1.48
A researcher estimates the 95% CI for a sample with a mean of M = 3.26 and a standard error (σM) of 0.91. What is the lower confidence limit for this interval?
One-sample t test
A researcher records the number of distracters (such as noises) that preschool-aged children ignore while watching a popular Sunday morning cartoon show. Assuming that the population variance is unknown, what type of t test is appropriate for this study?
η2 = 0.43 (large effect size)
A researcher reports a significant effect with t(14) = 3.24. Compute η2 for this result.
Two-tailed test because the p value is equal to .05.
A researcher reports that stress levels among nurses are higher compared to stress levels in the general population, t(20) = 2.086, p = .05 (d = .12). Was this a one-tailed or a two-tailed test?
12% of the variability in marketing effectiveness can be accounted for by the new marketing strategy.
A researcher reports that the effectiveness of a new marketing campaign significantly increased sales compared with the previous campaign strategy, t(49) = 2.562, p < .05. Use η2 to interpret the effect size for this result.
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?
Standard error of estimate
An estimate of the standard deviation or distance that data points fall from the regression line is measured by the ______.
True
The numerator of the formula for the slope ( b) of a regression line is equal to the sum of products.
False
The phi correlation coefficient is used to measure the correlation between two ordinal variables.
One is continuous and one is dichotomous
The point-biserial correlation coefficient is a measure of the direction and strength of the linear relationship between two variables, where ______.
True
The predictor variable is a known value that is used to predict the value of another variable.
True
The slope ( b) is a measure of the change in Y relative to the change in X.
False
The standardized beta coefficient, β, reflects the distinctive contribution of each criterion variable, including any overlap with other criterion variables.
True
To compute the standard error of estimate, we take the square root of the mean square residual.
Critical values
To summarize any type of regression analysis using APA format, we report each of the following except the ______.
Researcher B
Two researchers (A and B) compute a one-sample t test. For both tests, the standard error is the same, but the mean difference between the sample and value stated in the null hypothesis is smaller for Researcher A. Which test is more likely to result in a decision to reject the null hypothesis?
Square root of the mean square residual
What is the computation for the standard error of estimate?
True
When most of the variability in Y is attributed to regression variation, it is more likely that X predicts Y.
True
When scores are measured in a single group, the sample standard deviation is used as an estimate of the population standard deviation in the effect size formula for estimated Cohen's d.
The closer that data points fall to the regression line, the more the variance in Y will be attributed to regression variation.
Which of the following statements is true regarding the sources of variation present in an analysis of regression?
Standard error
Which type of error is used to compute the confidence interval for one sample selected from a population with a known variance?
True
A researcher states that the average child acquires 2.6 taste aversions in his or her lifetime. This is an example of a point estimate.
False
A t test is associated with N degrees of freedom.
