Answer: Consider the following four (x, y) data sets; the

Chapter 13, Problem 13.9

(choose chapter or problem)

Consider the following four (x, y) data sets; the first three have the same x values, so these values are listed only once Frank Anscombe, Graphs in Statistical Analysis, Amer. Statistician, 1973: 1721): For each of these four data sets, the values of the summary statistics xi , x2 i , yi , y2 i , and xiyi are virtually identical, so all quantities computed from these five will be essentially identical for the four setsthe least squares line (y 3 .5x), SSE, s2 , r 2 , t intervals, t statistics, and so on. The summary statistics provide no way of distinguishing among the four data sets. Based on a scatter plot and a residual plot for each set, comment on the appropriateness or inappropriateness of fitting a straight-line model; include in your comments any specific suggestions for how a straight-line analysis might be modified or qualified.