Education Technology

Describing Bivariate Data (Two Quantitative Variables)

Published on 06/09/2008

Activity Overview

Students explore the relationship between two quantitative variables in bivariate data using various x-y plots. They compare the relationships for several categories on the same plot. Students calculate the correlation coefficient to measure the strength and direction of the linear relationship that might exist between two variables.

Before the Activity

  • See the attached PDF file for detailed instructions for this activity
  • Print pages 23 - 26 from the attached PDF file for your class
  • During the Activity

    Distribute the pages to the class.

    Follow the Activity procedures:

  • Enter the distance versus time World Track records data for men and women (bivariate data) as a lists
  • Graph data as a scatter plot with each gender indicated by a different mark
  • Observe the linear relationship


  • Enter the automobile horsepower versus mileage data as lists
  • Graph the data as a scatter plot
  • Observe the inverse relationship
  • Determine the correlation coefficient


  • Graph building data versus year of completion data as a scatter plot
  • Note that the scatter is not linear and the correlation coefficient value is low


  • Graph the Olympic Marathon year versus time data as a x-y plot
  • Observe the time taken to run the marathon is decreasing


  • Use the given sample means UCL, center line, and LCL data, plot a x-bar control chart
  • After the Activity

    Review student results:

  • As a class, discuss questions that appeared to be more challenging
  • Re-teach concepts as necessary