STATISTICS

SCATTER PLOTS AND BEST-FIT LINES

A WebQuest for Algebra I

by Traci Spain

 

Introduction | Task | Resources | Process | Evaluation | Conclusion

Introduction

In order to determine if there is a relationship between two variables, data points are displayed in a graph called scatter plots. Scatter plots are two sets of data plotted as ordered pairs in a coordinate plane to model real-life data. Through a scatter plot a correlation is determined as positive, negative, or none at all. Predictions can also be made through scatter plots by using a best-fit line. A best-fit line is a line drawn passing close to most of the data points. A best-fit line determines whether the correlation is strong or weak.

In this unit, you will make a scatter plot and determine the correlation between the two variables. You will also make predictions using a best-fit line and write an equation of the best-fit line.

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The Task

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Classroom Resources

Internet Resources

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The Process

In this project you will use activities in Logal Express to make scatter plots and best-fit lines. You will be able to organize data so that you can make scatter plots and determine the correlation between the two given variables. On the scatter plots, you will be able to draw best-fit lines to make predictions about the given variables. You may use your class notes and your book as you go through these activities.

  1. Activity One: Getting Started - you need the information concerning scatter plots
  2. Activity Two: Weight vs. Time - you will use a scatter plot and best-fit line to see the connection between two sets of data---(double click on launch activity)
  3. Activity Three: Olympic Games-Appetizer - look at data (double click on launch activity) and continue on to The Olympic Games - observe scatter plot data and describe the pattern by drawing and approximate best-fit line and the actual best-fit line (do not continue)---(double click on launch activity)
  4. Activity Four: Earthquakes - examine data on major earthquakes, their magnitude, and their death toll
  5. Activity Five: Enrollment in Schools - use an Internet browser
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Evaluation

Each activity will be given a grade according to the rubric and its difficulty. The individual grades will be combined together to equal one test grade for this project.

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Conclusion

Through this project, you have organized data from two variables and made a scatter plot. Using the scatter plot, you were able to determine the correlation between the two variables. You also made predictions about the relationship between the two variables by drawing a best-fit line, as well as writing an equation of the best-fit line. As you can see real world problems can be solved using models, such as the scatter plot. Can you think of a situation in which a scatter plot would be a good representation of a set of data?

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