If a BOX= input data set is specified in PROC BOXPLOT and a character group variable is specified, the box plot tick mark labels on the horizontal axis will be incorrect. The first box plot label is skipped, the following labels are shifted over one position to the left, and the last box plot label is repeated twice so that only the last box has the correct label. For example, if the group or box plot values are A, B, C, D, E then they will be labeled B, C, D, E, E on the horizontal axis.

This problem does not occur with a numeric group variable, and all OUTBOX= data sets created by PROC BOXPLOT are correct.

To circumvent this problem, use a HISTORY= data set instead of a BOX= data set.