Use scatter plots to investigate and comment on relationships between two numerical variables (VCMSP352)

 

LO: To investigate and comment on scatter plots.

Know:

  • How to create a scatter plot from given data.

  • How to label a scatter plot graph with the x and y axis.

Understand:

  • That scatter plots can be used to represent a relationship between two factors (variables).

Do:

  • I can use scatter plots to investigate and comment on relationships between two numerical variables.

Elaborations

  • using authentic data to construct scatter plots, make comparisons and draw conclusions

Visual Representations

Scatter Plots

Scatter plots are an easy way of organising data from two categories into 1 graph. A scatter plot is a graph designed to show a relationship between corresponding numbers from two sets of data measurements associated with a single object or event. For example, a graph about marks and the corresponding amount of study time.

Basically, it’s identifying data from 2 categories then placing a dot (point) on a co-ordinate/Cartesian plane at where the data points correspond.

Relationships in Scatter Plots

Sometimes we can draw a generalization from the data that we see in a scatter plot.

If the data points are moving (trending) towards the upper right then it can be considered to have a positive correlation. Both variables are increasing at a similar rate.

If the data points are moving (trending) towards the bottom right then the data can be considered to have a negative correlation. Both variables are decreasing at a similar rate.

If the data points don’t present a trend (all over the place) then the data can be considered to have no correlation.

Positive Correlation

This is an example of a positive correlation, as students spent more time studying, the student grades also improved.

Negative Correlation

This is an example of a negative correlation, as students spent more time training, the time it took to run 100m decreased.

No Correlation

This is an example of no correlation, the colours in a rainbow have no relationship to the shoe size.

Teaching Ideas

  • compare two attributes or characteristics (e.g., height versus arm span), using a scatter plot, and determine whether or not the scatter plot suggests a relationship.

Creating a Scatter Plot Videos

Correlation Videos

Practise Questions

My Maths 9

Exercise 8F pg. 395 Q. 10-12

My Maths 10/10A

Exercise 10E pg. 507 Q. 1-5

Next Lesson – Standard Deviation