Interpreting Scatter Graphs

Relationships.

Scatter Graphs are an effective quick way of seeing if two variables (measures) have an effect upon each other.

e.g.  I think that the taller you are the heavier you will tend to be.  We can see if this relationship is evident if we take the measures of say 100 people and graph them.

Here are the results for the students in a class.  You can see that each person is represented by a cross (normally we use dots).  The tallest person is also the heaviest.


Line of Best Fit - can you see that there could be a straight line drawn into the graph over the points.  How closely can you see

Scatter Plot Intro

Bivariate Data 1.11 (aka 91036) Internal Three Credits

This counts for numeracy and literacy.  

For this we are going to compare numbers with numbers in a scatterplot (aka scatter graph).  We want for there to be a relationship (this is when the dots form a line).

We start with a question, draw the graph (and stats), write some sentences on what we see and write a conclusion.  This follows the PPDAC idea from the last topic.

Key Words...
Outlier - a dot (representing a person/car/country) that sits outside the line of best fit.
Line of Best Fit - a line best drawn between the dots.  You can hand draw this on.
Tightness - how closely to the line of best fit the dots are.