Policy makers have very good reason for wanting to know how common a condition or disease is. It allows them to plan and budget for treatment facilities, supplies of medication, rehabilitation personnel. There are two broad answers to the question, “How common is condition X?” and, interestingly, both of these use the exact same SAS…
Who was it that said asking a statistician about sample size is like asking a jeweler about price. If you have to ask, you can’t afford it. We all know that the validity of a chi-square test is questionable if the expected sample size of the cells is less than five. Well, what do you…
Recall that in the last post we were using SAS functions to score a test that had been completed by middle school and upper elementary students. Since we wanted to make it as easy as possible for students to enter their answers, we accepted just about any format. Picking up where we left off ……
Did you ever fill out one of those online forms where you kept trying to submit it and got messages like, “You need to enter your phone number in the format 311-234-12234” or You cannot have any special characters in this field. That one really irritates me because, in fact, my last name has a…
On twitter, there were a few comments from people who said they didn’t like to take interns because “More than doing work, they want to watch me work.” I see both sides of that. You’re busy. You’re not netflix. I get it. On the other hand, that’s a good way to learn. The data are…
Even though Rick Wicklin (buzzkill!) disabused me of the concern that SAS was communicating with aliens through the obscure coding in its sashelp data sets, I still wanted to roll my own. If you, too, feel more comfortable with a data set you have produced yourself, let me give you a few tips. There is…
I was going to write about prevalence and incidence, and how so-called simple statistics can be much more important than people think and are vastly under-rated. It was going to be cool. Trust me. In the process, I ran across two things even more important or cooler (I know, hard to believe, right?) Here’s what…
This is something that has bothered me for a long time. When I read tables and reports from the National Center of Education Statistics (yes, I do, don’t judge me!), it makes it sound as if all is well with rural education. According to this table, for example, 100% of rural schools have at least…
Over the weekend, I wrote a post showing how SAS can be used to make what appears to be a complex problem quite simple. First of all, am I just being dramatic? Seriously, how can having your variable lengths differ be a disaster? Simple. You are merging by a variable that is a unique user…
Some problems that seem really complex are quite simple when you look at them in the right way. Take this one, for example: My hypothesis is that a major problem in math achievement is persistence. Students just give up at the first sign of trouble. I have three different data sets with student data from the Spirit…