R Tutorial - #10 - Planned contrasts
Channel: Statistics for Doctors
Date: 2020-12-16

Sections:
0:00 Introduction
1:50 Import the data set (Alcohol and Self-control Study) and create a data frame
2:25 What are "contrasts"?
6:06 Seven Rules for building contrasts
13:57 Contrasts using the aov_4() function
19:53 Contrasts using the lm() function

I begin by explaining what a "contrast" is and then detail the so-called 'Seven Rules' for building contrasts. The rest of the tutorial explains how to apply these Seven Rules to the two functions we've been using to run contrasts for a one-way independent ANOVA. First, I explain how to run contrasts using the aov_4() function. Second, I explain how to run contrasts using the lm() function.

To freely download the R code and data sets used in this tutorial series, visit http://github.com/Statistics4Doctors. This tutorial analyzes a data set modified from data built by Dr. Andy Field (https://www.youtube.com/user/ProfAndyField) for his textbooks on statistics: Discovering Statistics using R (https://tinyurl.com/y6r6wsot) and SPSS (https://edge.sagepub.com/field5e).