Lesson 6: Percentiles and Boxplots

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September 6, 2016 at 11:00 am  •  Posted in f16-busad265 by  •  2 Comments

Wed, Sep 7

Review:

  • Measuring Center with Mean and Median
  • Problems with Median – SORT!
  • Tutoring available Thursdays 4-6pm in GCB 201 with David Mould

Presentation:

  • Example: Kick/Punt returns by Charles Nelson during Oregon vs UC Davis game Sat, Sep 3
    • {-2, 16, 27, 31, 33, 38, 46, 62}
    • n = 8
    • mean = 31.4
    • median = 31 (position 4)
    • 25th percentile = 16 (position 2)
    • 75th percentile = 38 (position 6)
    • Min = -2
    • Max = 62

Activity:

  • Product Boxplots (by hand)
    • Find the five number summary for Female height and Male height from the Student Survey data
    • Draw 2 boxplots, side by side, for comparison purposes.
    • Use the same scale for both box plots
    • Repeat using the World Population estimate data
      • Draw 4 boxplots, one per time period, side by side
      • Use the same scale for all 4 boxplots

Assignment:

  • Read pp. 34-38 (Quartiles, Five number summary, Boxplots)
  • Watch Boxplots with Google Sheets
  • Use Google Sheets
    • Make a Copy of RE East Pueblo
    • For each of the 3 neighborhoods: Belmont, Eastside and University
      • Use the “Selling Price” variable (see Column I)
      • Generate the 5 number summary
        • Calculate the mean, median, 25th and 75th percentiles
        • Identify the min and max values
    • Produce 3 boxplots
      • One boxplot per neighborhood, i.e., Belmont, Eastside and University
      • Plot together on the same chart for side-by-side visual comparison
      • This means using the same scale for all 3 boxplots
      • You’re welcome to use Sheets or you can do it by hand (if done neatly)

2 Comments

  1. Rique Lucero / September 9, 2016 at 8:06 pm / Reply

    I used sheets on my android phone. To be able to use the candlestick trend chart, I only get to use 4 arguments, not 5 as per the book. It asks for the min, open, close and max. So I used the min value, Q1 for open, Q3 for closed and max value. I then created the mean and median values separately so they will be charted next to their respective data group (belmont, mean, median….eside,mean,median) would this be okay for tests, or do I HAVE to have the median in the candlestick?

    • Justin / September 11, 2016 at 10:55 am / Reply

      Sounds like you found a good trick for making boxplots. If the visualization works well in terms of showing the spread of the data and how the different neighborhoods compare then I’m good with it.

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