Statistical Software

What Really Makes R So Hard to Learn?

September 19th, 2017 by

If you are like I was for a long time, you have avoided learning R.

You’ve probably heard that there’s a steep learning curve. Or noticed that the available documentation is not necessarily user-friendly.

Frankly, both things are true, to some extent.

R is Open-Source

The best and worst thing about R is that it is open-source. So there is no single (more…)


Tricks for Using Word to Make Statistical Syntax Easier

March 13th, 2017 by

We’ve talked a lot around here about the reasons to use syntax — not only menus — in your statistical analyses.

Regardless of which software you use, the syntax file is pretty much always a text file. This is true for R, SPSS, SAS, Stata — just about all of them.

This is important because it means you can use an unlikely tool to help you code: Microsoft Word.

I know what you’re thinking. Word? Really?

Yep, it’s true. Essentially it’s because Word has much better Search-and-Replace options than your stat software’s editor.

Here are a couple features of Word’s search-and-replace that I use to help me code faster:

(more…)


Creating Graphs in Stata: From Percentiles to Observe Trends (Part 2)

September 23rd, 2016 by

In a previous post we discussed the difficulties of spotting meaningful information when we work with a large panel data set.

Observing the data collapsed into groups, such as quartiles or deciles, is one approach to tackling this challenging task.  We showed how this can be easily done in Stata using just 10 lines of code.

As promised, we will now show you how to graph the collapsed data. (more…)


Converting Panel Data into Percentiles to Observe Trends in Stata (Part 1)

September 20th, 2016 by

Panel data provides us with observations over several time periods per subject. In this first of two blog posts, I’ll walk you through the process. (Stick with me here. In Part 2, I’ll show you the graph, I promise.)

The challenge is that some of these data sets are massive. For example, if we’ve collected data on 100,000 individuals over 15 time periods, then that means we have 1.5 million cells of information.

So how can we look through this massive amount of data and observe trends over the time periods that we have tracked? (more…)


Understanding Interaction Between Dummy Coded Categorical Variables in Linear Regression

September 2nd, 2016 by

The concept of a statistical interaction is one of those things that seems very abstract. Obtuse definitions, like this one from Wikipedia, don’t help:

In statistics, an interaction may arise when considering the relationship among three or more variables, and describes a situation in which the simultaneous influence of two variables on a third is not additive. Most commonly, interactions are considered in the context of regression analyses.

First, we know this is true because we read it on the internet! Second, are you more confused now about interactions than you were before you read that definition? (more…)


Incorporating Graphs in Regression Diagnostics with Stata

May 24th, 2016 by

Stage 2You put a lot of work into preparing and cleaning your data. Running the model is the moment of excitement.

You look at your tables and interpret the results. But first you remember that one or more variables had a few outliers. Did these outliers impact your results? (more…)