What techniques can be used to determine the median and range of data?
Determining central tendency and variation through media and range.
Median values are a measure of central tendency that determine the middle value of a rank-ordered series of data points.
Please see the attached file for a description of how to measure median values and for example calculations.
The difference between the highest and lowest measurements in a group of data is called the range. The range is a relatively crude measure of variability because it only considers the highest and lowest measurements. A sample range usually does not contain the highest and the lowest values possible for a given parameter; for this reason, the range usually underestimates the true range for a parameter. Range is used most frequently to characterize a parameter that may adversely affect a system. The range of pH in a wastewater treatment plant is an obvious example. An activated sludge plant with an influent pH measurement outside the normal 6.5 to 8.5 pH range may be headed for an upset. Under normal circumstances, the range of a data set can be determined by a visual examination of the data points.