Question 6.95

60. Return to Table 5.13 (page 226), which lists the top 100 baseball players ranked by career batting average. Consider only the top 50 players—Ty Cobb to Chuck Klein. Enter the data on career batting averages and career home runs into an Excel spreadsheet or calculator lists.

  1. Without first looking at the data, would you expect the correlation to be positive, negative, or close to zero? Explain.
  2. Calculate the correlation between career batting average and career home runs. What, if anything, does this tell you about the relationship between career batting averages and career home runs?
  3. Make a scatterplot of career batting average against career home runs. What, if anything, can we learn about career batting averages and career home runs from looking at this scatterplot?
  4. Find the equation of the least-squares regression line for predicting career home runs from a career batting average. Given what you know from parts (b) and (c), do you think this equation will yield reasonably accurate predictions? Explain.