SLIDE 1
The Scatterplot
- With two quantitative values from the same source (e.g. from
the same person), we can represent each case (e.g., person) as a point in 2D space.
- If we plot all of these points, we obtain a scatterplot
STAT 113 Scatterplots and Correlation Colin Reimer Dawson Oberlin - - PowerPoint PPT Presentation
STAT 113 Scatterplots and Correlation Colin Reimer Dawson Oberlin - - PowerPoint PPT Presentation
STAT 113 Scatterplots and Correlation Colin Reimer Dawson Oberlin College September 15, 2017 1 / 8 The Scatterplot With two quantitative values from the same source (e.g. from the same person), we can represent each case (e.g., person) as
SLIDE 2
SLIDE 3
Scatter Diagrams Show Patterns
Do you see a pattern? 3 / 8
SLIDE 4
Correlation
- You can identify correlations on a scatter diagram by the
distinct patterns they form.
- The variables are said to have a linear association if the
scatter diagram shows the points clustered around an approximately straight line.
- (Pearson’s) correlation coefficient measures the strength and
direction of this association. 4 / 8
SLIDE 5
Positive Linear Association
5 / 8
SLIDE 6
Negative Linear Association
6 / 8
SLIDE 7
No Association
7 / 8
SLIDE 8