Chi Square

8 Concepts
Scatterplots

3 Concepts
Simple Linear Regression

5 Concepts
Analysis of Variance (ANOVA)

6 Concepts
Summary of Fit

3 Concepts
Parameter Estimates

1 Concept
Confidence Intervals (Part 2)

3 Concepts
Prediction Intervals

2 Concepts
Hypothesis Tests (Part 2)

2 Concepts
**Extrapolation** occurs when x-values or y-values fall **outside the reasonable range** of values that would occur.

**Scenario**: Crammer Nation University wants to develop a regression equation to predict the "Number of Recruits" a given fraternity will receive this rush season given the "Parties Thrown" by the fraternity last year. They take a random sample of 52 fraternities on campus, resulting in the regression output below.

**y-hat** = 85.8312 + 20.5313(**x _{1}**)

This regression line assumes and *infinite number of students *at Crammer Nation University.

The fact of the matter is... a chapter can't get more recruits than the entire student population! The dotted portion of the red line represents this extrapolation of our linear regression!

Imagine a chapter threw 45 parties...

**y-hat** = 85.8312 + 20.5313(45)**y-hat** = 85.8312 + 923.9085**y-hat** = 1009.7397

The predicted value is 1009.7397 recruits... but the entire student population at Crammer Nation University is 750 students!

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