Regression Analysis Microsoft® Excel®

Contents

Introduction

1 Measuring Variation: How Values Differ

How Variation Is Measured

Sum of Deviations

Summing Squared Deviations

From the Sum of Squares to the Variance

Using the VAR.P() and VAR.S() Functions

The Standard Deviation

The Standard Error of the Mean

About z-Scores and z-Values

About t-Values

2 Correlation

Measuring Correlation

Expressing the Strength of a Correlation

Determining a Correlation’s Direction

Calculating Correlation

Step One: The Covariance

Watching for Signs

From the Covariance to the Correlation Coefficient

Using the CORREL() Function

Understanding Bias in the Correlation

Checking for Linearity and Outliers in the Correlation

Avoiding a Trap in Charting

Correlation and Causation

Direction of Cause

A Third Variable ...