One learning outcome for Biology majors is that students “use quantitative reasoning to analyze and interpret data, including the use of statistics, data visualization, and other computational techniques.” Given the increasing complexity and size of data, it is becoming increasingly important to document steps used to create graphs and perform statistical analysis. Computational techniques are necessary to accomplish these tasks.
The open-source software “R” combines a versatile, free environment for statistical analysis with a powerful suite of data-visualization tools. While you will receive extensive training in using the graphical user interface (GUI), RStudio, in Math 135 or 137: Applied Calculus and Math 155: Introduction to Statistical Modeling, this document provides introductory information to get you up to speed on graphing and applying appropriate statistical tests in the lab component associated with the four introductory biology courses.
There are several learning objectives for this document:
In this course, we use the web-based version of RStudio, which is accessible to all Macalester students at http://www.macalester.edu/rstudio. You can login using your Macalester username and the last four digits of your student ID number as your password (if the first of these four digits is a zero, then your password is the last three digits of your ID number).
R is comprised of a series of modules, called packages. The packages contain libraries of commands that the computer carries out to perform a function. When you first start R, several packages are loaded and become ready to use. In order to extend the types of functions R can execute, you can identify and initiate additional packages. For our purposes, we need to load the “mosaic” package, which continues to be developed by Prof. Danny Kaplan (Macalester College), Prof. Randy Pruim (Calvin College), and Nick Horton (Amherst College).
You can access this package by entering the following command in your console pane. library(mosaic) When you log off, RStudio will save all of your commands and defined variables, so you will not need to type the above command each time you open RStudio.