Download presentation
Presentation is loading. Please wait.
Published bySilas McCormick Modified over 9 years ago
1
If the scatter is curved, we can straighten it Then use a linear model Types of transformations for x, y, or both: 1.Square 2.Square root 3.Log 4.Negative Reciprocal 5.Reciprocal Chapter 10: Re-expressing Data
2
The relationship between fuel efficiency (in miles per gallon) and weight (in pounds) for late model cars looks fairly linear at first:
3
A look at the residuals plot shows a problem:
4
We can re-express fuel efficiency as gallons per hundred miles (a reciprocal) and eliminate the bend in the original scatterplot:
5
A look at the residuals plot for the new model seems more reasonable:
6
Goals of Re-expression Goal 1: Make the distribution of a variable more symmetric.
7
Goal 2: Make the spread of several groups more alike, even if their centers differ.
8
Goal 3: Make the form of a scatterplot more linear and evenly spread.
9
Note: If the data has no 0 or negatives, log is very useful.
10
Why Not Use Curves of best fit? Slope and y-int of lines are easier to understand!
11
Chapter 10 Assignment #1 – 17 Odd
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.