R

Generalized Linear Models in R, Part 3: Plotting Predicted Probabilities

July 2nd, 2014 by

In our last article, we learned about model fit in Generalized Linear Models on binary data using the glm() command. We continue with the same glm on the mtcars data set (regressing the vs variable on the weight and engine displacement).

Now we want to plot our model, along with the observed data.

Although we ran a model with multiple predictors, it can help interpretation to plot the predicted probability that vs=1 against each predictor separately.  So first we fit a glm for only (more…)


Generalized Linear Models in R, Part 2: Understanding Model Fit in Logistic Regression Output

June 24th, 2014 by

In the last article, we saw how to create a simple Generalized Linear Model on binary data using the glm() command. We continue with the same glm on the mtcars data set (more…)


Generalized Linear Models in R, Part 1: Calculating Predicted Probability in Binary Logistic Regression

June 18th, 2014 by

Ordinary Least Squares regression provides linear models of continuous variables. However, much data of interest to statisticians and researchers are not continuous and so other methods must be used to create useful predictive models.

The glm() command is designed to perform generalized linear models (regressions) on binary outcome data, count data, probability data, proportion data and many other data types.

In this blog post, we explore the use of R’s glm() command on one such data type. Let’s take a look at a simple example where we model binary data.

(more…)


R Is Not So Hard! A Tutorial, Part 14: Pie Charts

March 27th, 2014 by

In Part 14, let’s see how to create pie charts in R. Let’s create a simple pie chart using the pie() command. As always, we set up a vector of numbers and then we plot them.

B <- c(2, 4, 5, 7, 12, 14, 16) (more…)


R Programming Video: 15 Tips for The Beginner

March 25th, 2014 by

One of our instructors–David Lillis–recently gave a talk in front of the Wellington R Users Group highlighting 15 Tips for using the R statistical programming language aimed at the beginner.

Below is a video recording of his presentation…

 


R Is Not So Hard! A Tutorial, Part 13: Box Plots

March 17th, 2014 by

In Part 13, let’s see how to create box plots in R. Let’s create a simple box plot using the boxplot() command, which is easy to use. First, we set up a vector of numbers and then we plot them.

Box plots can be created for individual variables or for variables by group (more…)