The following questions use this table, which can be downloaded here in Excel format in girls.xls. These data are the heights (in cm) of girls of different ages (in years). For the following questions, you may use software of your choice. (Our source is Siegel and Morgan, Statistics and Data Analysis: An Introduction, 2nd. ed., John Wiley and Sons, 1996. Their source is the 1980 World Almanac)

(a) What would be more reasonable here, to think of height as dependent on age or age dependent on height?

(b) Make a scatterplot of these data and describe what you see.

(c) Find the correlation between these two variables (age and height).

(d) It only makes sense to compute a correlation under certain circumstances. Why is it reasonable here?

(e) Interpret the correlation coefficient in terms of the growth of girls.