Psychologists in many countries use children’s human figure drawings (Draw-A-Person Intellectual Ability Test, or DAPIQ) to assess intellectual ability. Basically, a child is asked to draw full-body picture of himself or herself, and the drawing is scored and normed based on the child’s age. Researchers in New Zealand (Imuta et al., 2013) explored whether this type of test is correlated with the more standard intellectual test, the Wechsler Preschool and Primary Scale of Intelligence (WPPSI). They tested 100 four- and five-year-old children. The results are in the file DrawIQChild. 

a. Use the Corr/Regression applet to determine the equation of the least squares regression line. Identify all variables used in the equation. 

b. Is a linear model appropriate for these data? Explain. 

c. What is the value of the slope of the least squares regression line, and what does it mean in terms of the DAPIQ and WPPSI scores? 

d. What is the value of the coefficient of determination, and what does it mean in terms of WPPSI and DAPIQ scores? 

e. Use the regression model to predict the WPPSI score for someone with a DAPIQ score of 100. 

f. One of the subjects had a DAPIQ score of 100 and a WPPSI score of 82. Calculate the residual for this subject and explain what it means. 

g. Does the DAPIQ score seem to be a good predictor of the WPPSI score for these subjects?