# Week 8 — Regression

In this week, we are learning about linear regression with StatsModels. All the examples will use the StatsModels OLS (ordinary least squares) model, generally with the formula interface.

Activities:

## Single Regression

In this video, I introduce single-variable regression.

Slide Clarification

On slide 6, where I show the slope, intercept, and variance in a model, I have extended the plot to include 0 at the left end of the x-axis. This is to highlight the meaning of the intercept. It is important to note that the intercept is where the line crosses zero, not where it crosses the left Y-axis.

Also, when discussing this slide, I am imprecise but make it sound like the unexplained variance is the remainder after projecting the data onto the line. It is the variance remaining after subtracting the line. I am preparing a video for Week 9 that will provide more clarity on this relationship.

## Week 8 Quiz

Complete the Week 8 quiz in Blackboard.

## Regression Model Assumptions

Read Regression Model Assumptions from JMP.

## StatsModels Examples and User Guide

The following StatsModels pages document its OLS model:

## Assignment 4

Assignment 4 is due October 25, 2020.