Type and Strength of a Linear Relationship Directions: Predict the type and strength of the linear relationship between each pair of variables: weak negative, strong negative, weak positive, strong positive, or no linear relationship at all

Type and Strength of a Linear Relationship

Directions: Predict the type and strength of the linear relationship between each pair of variables: weak negative, strong negative, weak positive, strong positive, or no linear relationship at all.

4. Number of fruits and vegetables eaten per day and risk of heart disease

Statistical Significance of Correlation Coefficients

Directions: Determine whether the correlation coefficient is statistically significant at the specified level of significance for the given sample size. Assume that a scatter plot of the data shows a linear pattern. 10. r = -0.462, a = 0.05, n = 18  11. r=0.305, a = 0.05, n = 45 Scatter Plots and Correlation Directions: Complete the following objectives for each data set.

a. Draw a scatter plot.

b. Estimate the correlation in words (that is, positive, negative, or no correlation).

c. Calculate the correlation coefficient, r.

d. Determine whether r is statistically significant at the 0.01 level of significance.

14. The following table gives the average number of hours 12 junior high students were left unsupervised each day and their corresponding overall grade averages.

Hours Unsupervised and Overall Grade Averages

Hours Unsupervised 0 0 0.5 1.0 1.0 1.5 2.0 3.0 3.0 4.0 4.5 5.5 Overall Grade Average 96 91 88 92 94 91 87 85 81 80 77 72

Correlation Coefficients and Coefficients of Determination Directions: Complete the following objectives for each data set.

a. Calculate the correlation coefficient, r.

b. Determine if r is statistically significant at the 0.05 level of significance.

c. Calculate the coefficient of determination, r2.

d. Interpret the meaning of r2 for the given set of data.

19. The following table gives data collected on the birth weights of mothers and the birth weights of their babies. (Hint: To do calculations on these data, first convert the data to a single unit of measurement.)

Mothers' Birth Weights and Babies' Birth Weights

lb 6 6 7 8 7 7 7 6 9 6 9 8 6 5 6 5 Mother oz 6 2 9 10 6 15 7 5 3 10 3 9 1 0 1 0 lb 5 6 7 7 10 5 9 5 8 7 9 8 5 7 7 8 Baby oz 11 14 10 2 0 13 0 9 13 11 10 6 8 15 2 5