Page 25 - Quality control of pharmaceuticals (07-PA 704)
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The most widely used measure of central value is the mean, . The mean,
also called the arithmetic mean or the average, is obtained by
dividing the sum of replicate measurements by the number of
measurements in the set:
Measures of Central Tendency – Median
The median is the middle result when replicate data are arranged in
increasing or decreasing order. There are equal numbers of results that
are larger and smaller than the median.
For an odd number of results, the median can be found by arranging the
results in order and locating the middle result.
For an even number, the average value of the middle pair is used as
shown in Example 5-1.
The median is robust, i.e. it is not affected by extreme values or outliers.
The mode of a set of measurements is defined to be the measurement that
occur most often (with the highest frequency).
The most frequent value.
Large number of values necessary.
It is possible to have two or more modes.
