(Data file: BGS all) Refer to the Berkeley Guidance study described in Using the data file BGS all, consider the regression of HT18 on HT9 and the grouping factor Sex. Draw the scatterplot of HT18...

(Data file: BGS all) Refer to the Berkeley Guidance study described in Using the data file BGS all, consider the regression of HT18 on HT9 and the grouping factor Sex.

Draw the scatterplot of HT18 versus HT9, using a different symbol for males and females. Comment on the information in the graph about an appropriate mean function for these data.