Justin Holman is CEO of Aftermarket Analytics, where he leads efforts to develop cutting edge sales forecasting and inventory optimization technology for the Automotive Aftermarket. Prior to joining Aftermarket Analytics, Justin managed corporate consulting for the Strategy & Analytics division at MapInfo Corporation, leading major projects for retail clients including The Home Depot, Darden Restaurants, Bridgestone-Firestone, Sainsbury’s and New York & Company. Before that, Justin served as Vice President of Software Development at LogicTools, now part of IBM's supply chain application software group. Justin holds a B.A. from Claremont McKenna College, a Ph.D. from the University of Oregon and an Executive Management certificate from Northwestern University's Kellogg School of Management.


  • Felipe 11 years ago

    I am so confused. For problem 2.1. What would be the bin and what would be the frequency?

    • justinholman 11 years ago

      The bin is the same as the class interval. Take a look at the Demonstration Problem on pages 21-22 for an example. The first two columns in the Solution section display the “Interval” (or Bin) and the “Frequency”. Create one frequency distribution with 5 bins (i.e., Intervals) and one with 10 bins. The frequency distribution is simply a table displaying the interval and associated frequency, like the table on page 22 under the Solution heading. Once you’ve constructed the two tables write a few sentences to describe why you prefer 5 or 10 bins.

      I uploaded an Excel file that might be helpful. Look at the new content and link to Excel file in the post above.

  • justinholman 11 years ago

    Another question from a student: how do i make the frequency polygon for 2.7?
    For the frequency polygon you need to calculate the “Class Midpoint” for each interval and then create a line graph (preferably in Excel but a hand-drawn graph will suffice) connecting the class midpoints. You can read about Class Midpoint on p 20-21 and look at the Frequency Polygon example described on p. 25-26. Hope this helps.

  • Kyle Leuer 11 years ago

    How do you set up the histograms for question 2.7 in excel? Using the excel analysis pack, I’m having problems trying to use the histogram function because I don’t have raw data. Unless you know of a way to get around this, I’ll most likely just use a random set of numbers that fit the criteria of the problem.

    • justinholman 11 years ago

      You shouldn’t need the raw data. Instead of entering “10-under-20” as the Class Interval try entering the number 10. See the example Excel file that I posted at the end of the Exercise 2 description. Let me know if you’re still confused. You can also simply draw the histogram by hand or use “Class Midpoints” for both the frequency polygon (line graph) and the histogram (bar graph).

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