Articles by Jason Bryer

Conducting Assessments and Surveys with Shiny

February 23, 2016 | Jason Bryer

This post describes a framework for using Shiny for conducting, grading, and providing feedback for assessments. This framework supports any multiple choice format including multiple choice tests or Likert type surveys. A demo is available at or can be run locally as a Github Gist:
... [Read more...]

Shiny App for Bayes Billiards Problem

February 22, 2016 | Jason Bryer

Consider a pool table of length one. An 8-ball is thrown such that the likelihood of its stopping point is uniform across the entire table (i.e. the table is perfectly level). The location of the 8-ball is recorded, but not known to the observer. Subsequent balls are thrown one ... [Read more...]

Data Caching

July 28, 2014 | Jason Bryer

Data caching is not new. It is often necessary to save intermediate data files when the process of loading and/or manipulating data takes a considerable amount of time. This problem is further complicated when working with dynamic data that changes regularly. In these situations it often sufficient to use ... [Read more...]

str Implementation for Data Frames

June 5, 2014 | Jason Bryer

The str function is perhaps the most useful function in R. It provides great information about the structure of some object. When I teach R, especially for those coming from SPSS, the str function for data frames provides the information they are use to seeing on the variable view tab. ... [Read more...]

Rgitbook Package for Using R Markdown with Gitbook

April 22, 2014 | Jason Bryer

Last week I published an R script to interface with Gitbook. I received some positive feedback and decided to include all the code in an R package. This also allowed me to make some nice additions including default support for MathJax. It is currently available on Github and can be ... [Read more...]

Using Gitbook with R Markdown

April 18, 2014 | Jason Bryer

Gitbook has been getting some (deserved) attention. For those who haven’t seen it, Gitbook is a system to create really beautiful interactive web (or PDF and ebook) books. For me, the timing of discovering this framework could not be better as I am preparing documentation for propensity score analysis ... [Read more...]

Albany, NY R Users Group

March 20, 2014 | Jason Bryer

I have started an R Users Group for the Albany, NY area. Hopefully we get enough interest that we can host a meeting in the next couple of months. Please feel free to share with your colleagues and friends. Feel fr... [Read more...]

Function to Simplify Loading and Installing Packages

February 20, 2014 | Jason Bryer

One of the more tedious parts of working with R is maintaining my R library. To make my R scripts reproducible and sharable, I will install packages if they are not available. For example, the top of my R scripts tend to look something like this:
if(!require(devtools) | !require(ggplot2) | !require(psych) | !require(lme4) | !require(benchmark)) {
This has worked ... [Read more...]

Bootstrapping for Propensity Score Analysis

November 26, 2013 | Jason Bryer

I am happy to announce that version 1.0 of the PSAboot package has been released to CRAN. This package implements bootstrapping for propensity score analysis. This deviates from typical implementations such as boot in that it allows for separate sampling specifications for treatment and control units. For example, in the case ... [Read more...]

Workshop and Talk Slides from NEAIR Conference

November 12, 2013 | Jason Bryer

I am about to head home from my fifth time attending the North East Association for Institutional Research (NEAIR), this year in Newport, RI, which was just fantastic. Really great people, interesting talks, and good food. I again taught an Introduction to R and LaTeX for Institutional Research pre-conference workshop ... [Read more...]

Version 1.1 of the likert Package Released to CRAN

October 18, 2013 | Jason Bryer

After some delay, we are happy to finally get version 1.1 of the likert package on CRAN. Although labeled 1.1, this is actually the first version of the package released to CRAN. After receiving some wonderful feedback from useR! this year, we held back releasing until we implemented many of the feature ... [Read more...]

Version 0.9 of timeline on CRAN

May 9, 2013 | Jason Bryer

The initial version of the timeline package has been released to CRAN. This package provides creates timeline plots using ggplot2 in a style similar to Preceden. I would considered this beta quality as there are more features I would like to add but has enough functionality to possibly be useful ... [Read more...]

Gambler’s Run With Shiny

May 8, 2013 | Jason Bryer

I finally had an opportunity to play with Shiny, and I am very impressed. I have created a Github Project so head over there for the source code. There are a number of ways to distribute Shiny apps. If you are running R (and mostly likely you are if you ...
[Read more...]

Cut Dates Into Quarters

April 18, 2013 | Jason Bryer

Frequently I need to recode a date column to quarters. For example, at Excelsior College we have continuous enrollment so we report new enrollments per quarter. To complicate things a bit, our fiscal year starts in July so that July, August, and September represent the first quarter, January, February, and ... [Read more...]

i Before e Except After c

March 26, 2013 | Jason Bryer

When I went to school we were always taught the “i before e, except after c” rule for spelling. But how accurate is this rule? Kevin Marks tweeted today the following: »@uberfacts: There are 923 words in the English language that break the “I before E” rule. Only 44 words actually follow ... [Read more...]

Version 1.0 of multilevelPSA Available on CRAN

February 14, 2013 | Jason Bryer

Version 1.0 of multilevelPSA has been released to CRAN. The multilevelPSA package provides functions to estimate and visualize propensity score models with multilevel, or clustered, data. The graphics are an extension of PSAgraphics package by Helmreich and Pruzek. The example below will investigate the differences between private and public school internationally ... [Read more...]

Converting a list to a data frame

January 30, 2013 | Jason Bryer

There are many situations in R where you have a list of vectors that you need to convert to a data.frame. This question has been addressed over at StackOverflow and it turns out there are many different approaches to completing this task. Since I encou... [Read more...]
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