Learning Objectives You should be able to: Vocabulary Understand when it is appropriate to use a Scatter Graph. Draw a Scatter Graph using a suitable scale. Understand what is meant by Correlation. Recognize the different types of Correlation. Plot Lines of Best Fit. Use Lines of Best Fit to make Predictions. Understand related vocabulary (See below). Vocabulary SAMPLE, DATA, VARIABLE, X AXIS, Y AXIS, SCATTER GRAPH, RELATIONSHIP, POSITIVE CORRELATION, NEGATIVE CORRELATION, NO CORRELATION, LINE OF BEST FIT, PREDICTION.

Scatter Graphs and Correlation When 2 sets of data are collected from the same sample it is possible to draw a Scatter Graph of the results. The 2 data values for each of the members of the sample are plotted as coordinates. It is possible to spot patterns or relationships from the Scatter Graph. There are three main cases to consider: Variable 1 Variable 2 Positive Correlation No Correlation Negative Correlation

Can you think of any variables that might display a Positive Correlation?

Can you think of any variables that might display a Negative Correlation?

Can you think of any variables that might display No Correlation?

Drawing a Scatter Graph The Data: The table below gives the data for the marks in Math and Science exams for 10 students. Student Math Mark Science Mark A 39 45 B 32 37 C 40 41 D 91 84 E 87 93 F 75 80 G 71 64 H 36 I 58 51 J 60 50

The Scatter Graph for this data would look like the one below.

As there were no scores below 30, we can could adjust the x and y axis to start from 30 in each case.

It is possible to draw a line of best fit on the scatter graph to give a feel to the relationship.

The line of best fit can be used to make predictions about the data The line of best fit can be used to make predictions about the data. For Example, Student K got 59 on the Math test but was absent for the Science test. What mark might you expect Student K to get for the Science test?

Scatter Diagrams and Correlation Now it's Your Turn Attempt: Scatter Diagrams and Correlation

Lesson Wrap Up Do you: Vocabulary Understand when it is appropriate to use a Scatter Graph? Know how to draw a Scatter Graph using a suitable scale? Understand what is meant by Correlation? Recognize the different types of Correlation? Know how to plot Lines of Best Fit? Know how to use Lines of Best Fit to make Predictions? Understand related vocabulary? Vocabulary SAMPLE, DATA, VARIABLE, X AXIS, Y AXIS, SCATTER GRAPH, RELATIONSHIP, POSITIVE CORRELATION, NEGATIVE CORRELATION, NO CORRELATION, LINE OF BEST FIT, PREDICTION.