6. A study of child development measures the age (in months) at which a ch child

Question

6. A study of child development measures the age (in months) at which a ch child begins to talk and also the child's the age at which a child talks helps score on an ability test given several vears later. The study asks whe predict the later test score. The least-squares regression line of test According to this regression line, what happens (on the average other children? A. Their predicted test scores go down 110 points B. Their predicted test scores go down 1.3 points. C. Their predicted test scores go up 110 points. D. Their predicted test scores go up 1.3 points E. Their predicted test scores are 108.7. score y on age x is y 110-1.3x ) to children who talk one month later than Which of the following statements concerning residuals is A. 7. true? The sum of the residuals is always 0. B. A plot of the residuals is useful for assessing the fit of the least-squares regression line. C. The value of a residual is the observed value of the response minus the value of the response that one would predict from the least-squares regression line. D. An influential point on a scatterplot is not necessarily the point with the largest residual. 8. You are examining the relationship between x the height of red oak trees and y the number of acorns produced in a five year period. You calculate a correlation coefficient and a least-squares regression line of y on x. If you switched the variables (that is, let x number of acorns and y -height of trees), which of the following would be true? A. both the correlation coefficient and the regression line would be unchanged. B. the correlation coefficient would change, but the regression line would not change. C. the correlation coefficient would not change, but the regression line would change. D. neither the correlation coefficient nor the regression equation would change. E. only the y-intercept of the regression line would change, the slope of the line and the correlation coefficient would not change.

Explanation / Answer

6

If we increase x by 1 unit then Y will fall by 1.3. Hence the predicted score will be 108.7

Hence correct options are B and E

7

The statements about regression from A to D are correct.

Hence option E is the correct answer.

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