{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

OLS_Assumptions08B part 2

# OLS_Assumptions08B part 2 - Assumptions of Ordinary Least...

This preview shows pages 1–7. Sign up to view the full content.

1 Assumptions of Ordinary Least Squares Regression (Part 2) ESM 206 Jan 21, 2008

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2 7. Errors not normally distributed Problem: Parameter estimates are unbiased P-values are unreliable Regression fits the mean; with skewed residuals the mean is not a good measure of central tendency Diagnosis: examine QQ plot of residuals
3 -2 -1 0 1 2 -20 -10 0 10 20 30 40 norm quantiles Chlorophyll\$residuals.LinearModel.1 1. Save residuals to dataset using Models -> Add Observation Statistics to Data 2. Make a QQ plot

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
4 Errors not normally distributed Problem: Parameter estimates are unbiased P-values are unreliable Regression fits the mean; with skewed residuals the mean is not a good measure of central tendency Diagnosis: examine QQ plot of Studentized residuals Corrects for bias in estimates of residual variance -2 -1 0 1 2 -2 -1 0 1 2 3 norm quantiles Chlorophyll\$rstudent.LinearModel.1
5 1. Models -> Graphs -> Residual Quantile-Comparison Plot -2 -1 0 1 2 -2 -1 0 1 2 3 t Quantiles Studentized Residuals(LinearModel.1)

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
6 Errors not normally distributed Problem: Parameter estimates are unbiased P-values are unreliable
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern