1. Regression is the Most Used and Most Abused Technique in Statistics
Assumptions:
A line adequately models the data
Homoscedasticity – same scatter of points along entire line
Residuals at any given value of the explanatory variable are normally distributed
Residuals at any given value of the explanatory variable are independent
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Advanced
Linear Regression

2. A Line Models the Data
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Linear Regression

3. Homoscedasticity
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Linear Regression

4. Other Problems Outliers Influential Points
a problem because the model does not fit that point
may or may not remove
Influential Points
a point that would markedly change the line if it were removed
typically an outlier in the x direction
Linear Regression