Practice Quiz Chapter 10

. Out of the following terms, which one is not a type of relationship that can be depicted on a scatterplot?

. What is a monotonic relationship?

. What is a homoscedastic relationship?

. Pearson's correlation coefficient, like gamma, is symmetric. What does this mean?

. One of the following statements about correlation coefficients and scatterplots is not true. Which one is it?

. Which of the following statements does not apply to the calculation of the sum of products?

. What is the sum of products divided by in the calculation of covariance?

. Using the following hypothetical data calculate the Pearson's correlation coefficient: sum of products equals 173,000, SSx equals 86, and SSy equals 564,000,000.

. Interpret your answer from the question above: What does it mean for the two hypothetical variables the answer is based on?

. Using the following hypothetical data calculate the Pearson's correlation coefficient: sum of products equals 93,000, SSx equals 90, and SSy equals 446,000,000?

. Interpret your answer from the question above: What does it mean for the two hypothetical variables the answer is based on?

. Which of the following statements about correlation matrices is not true?

. What is the null hypothesis when using the t-distribution to assess the reliability of a correlation between two ratio-level variables in the population?

. Calculate the degrees of freedom necessary for the calculation of the t-statistic using the following values: r = 0.7 and n = 10. How many degrees of freedom are represented in this data?

. Calculate the t-statistic for the following values: r = 0.7 and n = 10. What is the t-statistic?

. In the questions above, you calculated the t-statistic and the degrees of freedom for the following values: r = 0.7 and n = 10. Find the p-value for the t-statistic with the degrees of freedom that you calculated. How would you interpret this p-value?

. Which of the following is not said about the Pearson's correlation coefficient?

. The Spearman's rank-order correlation coefficient possesses several properties. Which one of the following is not a property of this coefficient?

. Using the following hypothetical data calculate the Spearman's correlation coefficient: sum of products equals 67.5, SSx equals 86, and SSy equals 87?

. Interpret your answer from the question above: What does it mean for the two hypothetical variables the answer is based on?

. With a scatterplot, the independent variable is typically plotted on the vertical or y-axis and the dependent variable is typically plotted on the horizontal axis.

. A non-linear relationship refers to a relationship with any other type of pattern besides a straight line.

. A heteroscedastic relationship is one where the dispersion or spread of the dependent variable is roughly the same across all the values on the independent variable.

. A homoscedastic relationship is one where the dispersion or spread of the dependent variable is different or changes across the values on the independent variable.

. Often, researchers don't want to use all the cases in a dataset in their analyses.

. The magnitude of a relationship between two ratio-level variables is often described using a measure of association called Pearson's correlation coefficient.

. The Pearson's correlation coefficient provides information about the strength and direction of the linear relationship between two variables and is denoted with an upper case ‘R’.

. The sign of the correlation coefficient indicates the strength of the relationship and the size of the coefficient indicates whether a relationship is positive or negative.

. The sum of products is the sum of the products of the deviations from the mean.

. The first step in calculating the Pearson's correlation coefficient is to find the sum of products.

. The key difference between the sum of squares and the sum of products is that the sum of products captures variation around the mean of a single variable whereas the sum of squares captures covariation around the means of two variables in combination.

. If the sum of products is positive, there is a positive relationship between the two variables and if the sum of products is negative, there is a negative relationship between the two variables.

. The sum of squares is calculated in the same way as the total sum of squares in a one-way ANOVA test.

. Conceptually, Pearson's correlation coefficient is equivalent to the covariance, divided by the product of the standard deviation of each variable.

. The diagonal cells in a correlation matrix always show a correlation of 1.

. The order of the variables in a correlation matrix is never the same in the rows and in the columns.

. The reliability of a correlation between two ratio-level variables is assessed using a statistical significance test that relies on a t-distribution.

. ρ is the same as Pearson's correlation coefficient except that it is calculated using the rank of each case within a variable instead of the values on each variable.

. ? is a non-parametric test because it does not rely on any assumptions about the underlying distribution of a variable.

. A key similarity between Pearson's and Spearman's correlation coefficient is that both can be interpreted in relation to the standard deviation of each variable.

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