Does the Tukey method use the middle point or median number?
The Tukey method uses both the “median” and “middle” data points in establishing a trend. Here, the “median” refers to the middle score with respect to absolute value from an array of scores. The “middle” refers to the middle score with respect to relative position among a group of scores. For example, let’s say that you have the following scores in Phase I (33, 45, 36, 42, 44) and Phase III (52, 60, 58, 64, 68) (recall that collected scores are divided into three fairly equal groups in the first step of the process). In Phase I, “42” would represent the median score as it is the middle score with respect to absolute value (i.e., 33, 36, 42, 44, 45). Once the median is established, an “x” would be placed in Phase I at the place where 42 on the vertical axis and 36 on the horizontal axis meet. Why 36 on the horizontal axis? Because it represents the middle score with respect to relative position among the five scores. Here, absolute value is of no concern. We simply want to identify the
