Previously, I discussed PROC FREQ for checking the validity of your data. Now we are on to data analysis, but, as anyone who does analysis for more than about 23 minutes can tell you, cleaning your data and doing analysis is seldom a two-step process. In fact, it’s more like a loop of two steps,…
I’m in the middle of data preparation on a research project on games to teach fractions. This is the part of a data analysis project that takes up 80% of the time. Fortunately, PROC FREQ from SAS can simplify things. 1. How many unique records ? There are multiple quizzes in the game, and you…
I’m the world’s biggest hypocrite when it comes to documentation. In every staff meeting, I emphasize documenting whatever code you have written that week, but I always put off doing it myself. My excuse is always that it isn’t final and when I get the complete project done I will put it in the wiki….
Sometimes, you can know too much programming for your own good. Yesterday, I was working on analyzing a data set and can I just say here that SAS’s inability to handle mixed-type arrays is the bane of my existence. (In case you don’t know, if you mix character and numeric variable types in an array,…
I’m preparing a data set for analysis and since the data are scored by SAS I am double-checking to make sure that I coded it correctly. One check is to select out an item and compare the percentage who answered correctly with the mean score for that item. These should be equal since items are…
Do you have a bunch of sites bookmarked with articles you are going to go back and read later? It’s not just me, is it? One of my (many) favorite things at SAS Global Forum this year was the app. It included a function for emailing links to papers you found interesting. Perhaps the theory…
We’ve looked at data on Body Mass Index (BMI) by race. Now let’s take a look at our sample another way. Instead of using BMI as a variable, let’s use obesity as a dichotomous variable, defined as a BMI greater than 30. It just so happened (really) that this variable was already in the data…
So far, we have looked at How to get the sample demographics and descriptive statistics for your dependent and independent variable. Computing descriptive statistics by category Now it’s time to dive into step 3, computing inferential statistics. The code is quite simple. We need a LIBNAME statement. It will look something like this. The exact…
In the last post, I posed the following null hypothesis as an example: There is no difference in obesity among Caucasians, African-Americans and Latinos. You can see the results from the statistical analyses here. Since my question only pertains to those three groups, let’s begin by creating a data set with just those subjects. libname…
I get asked this question fairly often so I thought I would do a few posts on it. The most common problem is that a student who is new to statistics has no idea where to even start. These examples use SAS but you could use any package you like. My recommendation to students beginning…