Stats 128 Practice Test Questions 2024.

Stats 128 Practice Test Questions 2024. Match the linear correlation coefficient to the scatter diagram. The scales on the x- and y-axis are the same for each scatter diagram. (a) r = -1, (b) r = -0.049, (c) r = -0.992 - CORRECT ANSWER (a) = II, straight line down (b) = III, dots everywhere (c) = II, wider line down On an international exam, students are asked to respond to a variety of background questions. For the 41 nations that participated in the exam, the correlation between the percentage of items answered in the background questionnaire (used as a proxy for student task persistence) and mean score on the exam was 0.728. Does this suggest there is a linear relation between student task persistence and achievement score? Write a sentence that explains what this result might mean. Does this suggest there is a linear relation between student task persistence and achievement score? Choose the best response below. What does this result mean? - CORRECT ANSWER A. Yes, since |0.728| is greater than the critical value for 30. B. Countries in which students answered a greater percentage of items in the background questionnaire tended to have higher mean scores on the exam. A pediatrician wants to determine the relation that exists between a child's height, x, and head circumference, y. She randomly selects 11 children from her practice, measures their heights and head circumferences, and obtains the accompanying data. Complete parts (a) through (g) below. - CORRECT ANSWER (a) Find the least-squares regression line treating height as the explanatory variable and head circumference as the response variable. Y = 0.177x + (12.768) (b) Interpret the slope and y-intercept, if appropriate. Interpret the slope. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. C. For every inch increase in height, the head circumference increases by 0.176 in., on average. Interpret the y-intercept, if appropriate. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. E. It is not appropriate to interpret the y-intercept. (c) Use the regression equation to predict the head circumference of a child who is 25 inches tall. Y = 17.18 in. (Round to two decimal places as needed.) Compute the residual based on the observed head circumference of the 25-inch-tall child in the table. Is the head circumference of this child above or below the value predicted by the regression model? The residual for this observation is -0.28, meaning that the head circumference of this child is below the value predicted by the regression model. (Round to two decimal places as needed.) (e) Draw the least-squares regression line on the scatter diagram of the data and label the residual from part (d). Choose the correct graph below. (b) check graphs better Notice that two children are 26.5 inches tall. One has a head circumference of 17.4 inches; the other has a head circumference of 17.6 inches. How can this be? B. For children with a height of 26.5 inches, head circumferences vary. (g) Would it be reasonable to use the least-squares regression line to predict the head circumference of a child who was 32 inches tall? Why? D. No - height is outside the scope