I tell clients on our statistical consulting side all of the time that if your conclusion is only valid if you look at this specific subset of your sample, with this particular statistical technique. You need to look for a convergence or results. Does the mean score increase? Does the proportion of people passing a…
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…
For many students just learning statistics, the relationship of z-scores and probability is confusing. Let’s try this concrete example. Here is a chart of the distribution of height in a sample of over 2,800 women. Notice that the peak, the mode is around 62-63 inches. You can see the frequency table here, as well as a…
First off, the good news. You can find all of the papers from SAS Global Forum 2015 online. This is good news if you are anything like me (and you should be, because, let’s face it, I’m awesome) because even if you went to Dallas there were no doubt several papers you wanted to attend…
I finally am getting around to something in SAS Studio that I think is really cool – the tasks. Although they don’t look identical to SAS Enterprise Guide just because the screen layout is a little different, these are really, really similar to the tasks you would see in EG. If you are using this…