what values are used in a box plot
And different software packages use all different sorts of formulas. Be careful to use the formula from your book when doing your homework! Additionally, the box-and-whisker plot may include a cross or an X marking the mean value of the data, in addition to the line inside the box that marks the median. The difference between the X and the median line can then be used as a measure of skew. Please don't ask me to explain skew.