MANG 575 Module 3: Measures of Location and Dispersion


  • Understand the difference between a population and a sample
  • Be able to calculate an arithmetic mean, weighted mean, median and mode
  • Be able to interpret the mean, median and mode and explain its mean within the context of a set of data
  • Be able to calculate measures of dispersion such as the range, variance and standard deviation
  • Be able to interpret the range, variance and standard deviation and explain its mean within the context of a set of data
  • Understand the Empirical Rule as it relates to a set of data

Reading For This Module:

Chapter 3 – Textbook
Textbook Power Point(.ppt)

Opening Vignettes:


This chapter looks at data from two different perspectives; measures of location and measures of dispersion.Measures of location are primarily concerned with concept of average.  You no doubt have calculated an average before.  For example, the average price of a home in the US is $135,000 and on average has 3 bedrooms and 2 bathrooms.  This of course doesn’t indicate that all homes have these attributes because obviously some homes are large and more expensive, while others are smaller and less expensive. Another example is the average high temperature in Farmville, VA during January is 46 degrees while the average low is 25 degrees. We may also calculate the average test scores in a statistics class. However, consider this example where five students take their exam with the following grades 95, 95, 90,90 and 15.  The average on this exam is 77.  Does this truly reflect the difficulty of the exam? The above example is just one reason why are looking at only the average can lead one to draw an erroneous conclusion. by just looking at the average it appears that the class on average burned a grade of “C” when in actuality four out of the five students earned an “A”.Now consider the grades of another five students each of which earned the following grades; 79, 75, 78, 76, 77.  The average exam score for these five students is also 77.  You can see that averages alone can be a bit deceiving.  This is why it is important to look at measures of dispersion along with measures of location.  The measures of dispersion that we will focus on mainly are variance in standard deviation .  You may hear people talk about the volatility or spread of the data, variance and/or standard deviation is what they are speaking of.



Dr. Waller Lecture: Topic Name (video)

Lecture Power Points (.pptx)


Summary of this module.

Practice Quiz

Practice Quiz for this module, feel free to take multiple times


Take the quiz for this module on Canvas.


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