Exploring correlation between variables is an important part of exploratory data analysis. Before you start to model data, it is a good idea to visualize how variables related to one another. Zach Mayer, on his Modern Toolmaking blog, posted code that shows how to display and visualize correlations in R.
You can generate a set of random numbers in SAS that are uniformly distributed by using the RAND function in the DATA step or by using the RANDGEN subroutine in SAS/IML software. (These same functions also generate random numbers from other common distributions such as binomial and normal.) The syntax
One of the great innovations with SAS 9.3 is the focus on ODS statistical graphics. "Wait a minute," you're thinking, "weren't ODS graphics added in SAS 9.2?" Yes, that's true. But with SAS 9.3 there is even more capability: more analytical SAS procedures support the graphs, and there are more
As I was reviewing notes for my course "Data Simulation for Evaluating Statistical Methods in SAS," I realized that I haven't blogged about simulating categorical data in SAS. This article corrects that oversight. An Easy Way and a Harder Way SAS software makes it easy to sample from discrete "named"
It seems like such a simple problem: how can you reliably compute the age of someone or something? Susan lamented the subtle issues using the YRDIF function exactly 1.0356164384 years ago. Sure, you could write your own function for calculating such things, as I suggested 0.1753424658 years ago. Or you
SAS Enterprise Guide sets values for several useful SAS macro variables when it connects to a SAS session, including one macro variable, &_CLIENTPROJECTPATH, that contains the name and path of the current SAS Enterprise Guide project file. (To learn about this and other macro variables that SAS Enterprise Guide assigns,
The recent issue of InformationWeek features a Q&A session with Ken Thompson, one of the creators of the Unix operating system. (He collaborated with Dennis Ritchie, of C language fame. Since much of SAS is written in C, I daresay there are a few copies of K&R around here.) One
Jittering. To a statistician, it is more than what happens when you drink too much coffee. Jittering is the act of adding random noise to data in order to prevent overplotting in statistical graphs. Overplotting can occur when a continuous measurement is rounded to some convenient unit. This has the
In my statistical analysis of coupons article, I presented a scatter plot that includes the identity line, y=x. This post describes how to write a general program that uses the SGPLOT procedure in SAS 9.2. By a "general program," I mean that the program produces the result based on the
About a year ago (wow, has it been that long?), I posted an example program that lets you report on the contents of a SAS information map. Using my example, you can see the data items, filters, and folder structure within a given information map. Last week a reader posted
This is Part 4 of my response to Charlie Huang's interesting article titled Top 10 most powerful functions for PROC SQL. As I did for eaerlier topics, I will examine one of the "powerful" SQL functions that Charlie mentions and show how to do the same computation in SAS/IML software.
SAS-based processes are critical to many organizations, but sometimes the trickiest part of your job falls into one or both of these activities: Getting stuff from the outside world "into" SAS. (Once it's in SAS, as many of you know, the world is your oyster.) Getting the output of your
When Charlie H. posted an interesting article titled "Top 10 most powerful functions for PROC SQL," there was one item on his list that was unfamiliar: the COALESCE function. (Edit: Charlie's blog no longer exists. The article used to be available at http://www.sasanalysis.com/2011/01/top-10-most-powerful-functions-for-proc.html) Ever since I posted my first response,
It's a simple task to use SAS to compute the number of weekdays between two dates. You can use the INTCK function with the WEEKDAY interval to come up with that number. diff = intck('WEEKDAY', start_date, end_date); If you want to compute the number of working days between two dates,
Last week I showed how to create a funnel plot in SAS. A funnel plot enables you to compare the mean values (or rates, or proportions) of many groups to some other value. The group means are often compared to the overall mean, but they could also be compared to
This morning I delivered a talk to visiting high school students at the SAS campus. The topic: using SAS to analyze Twitter content. Being teenagers, high school students are well familiar with Twitter. But this batch of students was also very familiar with SAS, as they all have taken SAS
String comparisons in SAS software are case-sensitive. For example, the uppercase letter "F" and lowercase letter "f" are treated as unique characters. When these two letters represent the same condition (for example, a female patient), the strings need to be handled in a case-insensitive manner, and a SAS programmer might
The Flowing Data blog posted some data about how much TV actors get paid per episode. About a dozen folks have created various visualizations of the data (see the comments in the Flowing Data blog), several of them very glitzy and fancy. One variable in the data is a categorical
Millions of Americans will be gathering around the television this Sunday to watch Super Bowl XLV. They'll gather in bars and private homes, prepare billions of calories worth of snacks, and root for their favorite teams. But if you're looking for an alternate form of entertainment, why not watch "New
As Cat Truxillo points out in her recent blog post, some SAS procedures require data to be in a "long" (as opposed to "wide") format. Cat uses a DATA step to convert the data from wide to long format. Although there is nothing wrong with this approach, I prefer to
A colleague related the following story: He was taking notes at a meeting that was attended by a fairly large group of people (about 20). As each person made a comment or presented information, he recorded the two-letter initials of the person who spoke. After the meeting was over, he
The Junk Chart blog discusses problems with a chart which (poorly) presents statistics on the prevalence of shark attacks by different species. Here is the same data presented by overlaying two bar charts by using the SGPLOT procedure. I think this approach works well because the number of deaths is
A customer phoned up SAS Technical Support the other day with a problem. (Yes, that happens occasionally...) When he ran a certain program through SAS Enterprise Guide, the program didn't seem to complete and no results were returned. Here is a snippet of the program (modified a bit to make
You might be too young to remember Clara Peller. She was the star of a series of fast-food burger commercials in the 1980s, in which she demanded meatier meals by shouting "Where's the beef?" at the pickup counter or drive-through window. Alas, the competitor restaurant meals were afflicted with "Fluffy
Let's pretend for a moment that you don't have SAS installed on all of your office computers. But you've got some great content locked away inside SAS data sets. Is there a way to get to the content of that data, without having to push the data through a SAS
The question came up on the SAS Enterprise Guide discussion forum: which do you prefer, List Report Wizard (PROC REPORT) or Summary Tables (PROC TABULATE)? And as with most SAS-related questions, the proper response is: "it depends." If you put these two PROCs in the ring with a Google Fight,
In a previous post, I discussed how to generate random permutations of N elements. But what if you want to systematically iterate through a list of ALL permutations of N elements? In the SAS DATA step you can use the ALLPERM subroutine in the SAS DATA step. For example, the
Yesterday, I was in the #raganSAS audience as David Pogue told me What's New and What's Next in the world of technology. David is a great presenter, and he really had the audience engaged as he talked about augmented reality, his world according to Twitter, and an iPhone app that
I saw a suggestion arrive from a SAS customer who would like to see the IN operator extended to allow ranges of date values. For example, you can currently write a program that checks for values IN a collection or range of numbers: data check; if x in (1:10) then
Have you ever visited a city for the first time and, instead of relying maps to plan your journey, you simply plug your destinations into a GPS device and mindlessly follow the navigation directions? You've just cheated yourself out of a learning opportunity, because planning the journey and using your
