Lesson 4: Measuring Variance and Standard Deviation

August 29, 2024

Review:

• Measures of Center and Boxplots
  • Mean, Median, Percentiles, Quartiles
  • Five-number summary
  • Min, Q1, Median, Q3, Max
  • Quartiles and Boxplots (U. Illinois)
  • Boxplot Grapher: http://www.imathas.com/stattools/boxplot.html
• Lifetime earnings by education attainment
  • https://www.ssa.gov/policy/docs/research-summaries/education-earnings.html
  • https://nces.ed.gov/programs/coe/indicator/cba/annual-earnings
  • https://www.bls.gov/emp/chart-unemployment-earnings-education.htm
  • https://www.nytimes.com/2018/01/04/learning/whats-going-on-in-this-graph-jan-9-2018.html
• Attendance

Presentation:

• Demonstrate calculation
  • Find the variance and the standard deviation for the following (n=10) exam scores:
    • 80 73 92 85 75 98 93 55 80 90
    • See text p. 40-42
  • Demonstrate by hand
  • Demonstrate in Google Sheets
• Against All Odds – Video Unit 6

Activity:

Problem 1. Below are the number of home runs that Babe Ruth hit in each of his 15 years with the New York Yankees, 1920 – 1934. Calculate the mean and standard deviation.
54 59 35 41 46 25 47 60 54 46 49 46 41 34 22 

Problem 2. Six 9th-grade students and six 12th-grade students were asked: how many movies have you seen this month? See their responses below. Calculate the mean and standard deviation for each data set. Which is more spread out, the 9th-grade or 12th-grade data?
9th-grade: 5, 1, 2, 5, 3, 8
12th-grade: 4, 2, 0, 2, 3, 1

Prepare a Google Slides file to serve as a portfolio of your in-class and homework activities.

Assignment:

• Repeat Problems 1 and 2 (above) using Sheets
• Update your Google Slides Portfolio
• Text Ch. 1, p. 40-44