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Using the ‘Median’ as a Measure of Central Tendency
A measure of central tendency is a single value that describes the way in which a set of data cluster around a central value. In other words, it is a way to describe the center of a data set.
The three main measures of central tendency are:
Median of the Distribution
In very simple terms; when your set of data is arranged in order from smallest to largest, the medianIn statistics and probability theory, the median is the... Learn More... is the literal middle of the data set. For an odd sized sample, the median is equal to the literal middle number. To find the median in an even sized sample, you have to add the two middle numbers and then divide the result by two.
The median of a distribution of data is determined as the 50th percentile point once the distribution has been defined.
For normal distributions, the median value occurs at or close to the mean of the distribution. This is also where the mode, or high point (most frequently occurring value), of the distribution occurs.
For distributions that are skewed to the left, both the median and modeThe mode is the value that appears most often in a set of ... Learn More... occur to the left of (are smaller than) the average of the distribution.
For distributions that are skewed to the right, both the median and mode occur to the right of (are larger than) the average of the distribution.
Finding skewed distributions in a Lean Six Sigma project?
I normally find skewed distributions in data representing time. For example, a call center’s time to resolve a level one help desk ticket. The call center is continuously trying to decrease the time to resolve a levelThe value of an input in an experimental run. one help desk ticket. The data set should show that most of the data should cluster closer to zero. This would represent skewed data that would have a central tendency best described by the median.
Let me know in the comments below, if you have ever encountered skewed distributions in your Lean Six SigmaSix Sigma Definition: Six Sigma is a set of techniques and t... Projects and how did you analyze them?
Hi, I always enjoy your blog posts and information – very helpful to keep the tools in mind.
I noticed in this one that the text descriptions do not match the associated figures – “For distributions that are skewed to the left, both the median and mode occur to the left of (are smaller than) the average of the distribution” and “For distributions that are skewed to the right, both the median and mode occur to the right of (are larger than) the average of the distribution” do not match what is shown in the images.