Median Trend Chart and Interpretation

Trend Chart – A line graph of data plotted over time

  • Generally, 25 data points are needed to get meaningful results
  • Plot the values on the chart and connect the dots.
  • Calculate the median and place this on the chart. The median is the value separating the higher half of a data from the lower half.
  • In the data set {1, 3, 3, 6, 7, 8, 9}, the median is 6
  • In the data set (1,2,3,4,5,6, 8,9) the median is 4+5 / 2 = 4.5

Interpretation *

  • 5 Points in a row rising or falling indicates a change in the process
  • 6 Points in a row above or below the median also indicates a change
  • Points (outliers) that appear farther away from the median than others may indicate either a change or a temporary or unusual event
  • Also look for nonrandom patterns – too close or too far from the median, or cycles. The people closest to the process may be able to provide an explanation of the behavior

* Acceptable standards range anywhere from 5-8 data points. Can also just use 7.

More Info:

Run Chart: Creation, Analysis, & Rules

Right number or Right Action?

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