Tossing dice is a simple and familiar process, yet it can illustrate deep and counterintuitive aspects of random numbers. For example, if you toss four identical six-sided dice, what is the probability that the faces are all distinct, as shown to the left? Many people would guess that the probability
Mit welchen IT-Innovationen können Finanzdienstleister Ihre größten Herausforderungen (Regulierung, Risikoanalyse, Unternehmensarchitektur) nachhaltig unterstützen? Hier sehe ich vor allem: Schlanker werden durch Industrialisierung, indem die zahllosen Silostrukturen abgebaut werden, die eine integrierte Steuerung behindern! Die Industrialisierung dieser Strukturen - ähnlich der Plattformstrategien in der Automobilindustrie - führen zu enormen Effizienzgewinnen, einer
Echtzeit? Den Algo-Tradern wird das jetzt ein Lächeln auf die Lippen zaubern. Natürlich rede ich in diesem Zusammenhang nicht über Milli- oder Mikrosekunden, aber über Antwortzeiten die für einen Fachanwender akzeptabel sind, um interaktiv mit einer analytischen Applikation zu arbeiten. In diesem Fall darf sich nämlich eine solche Anwendung schon
Schnell erkennen, schnell handeln und schnell vorankommen bietet schon einige Vorteile. Aber wir sollten uns davor schützen, schnell in die falsche Richtung zu rennen. Mir fällt hierzu das Bild des Marathonläufers ein, der in führender Position die falsche Abzweigung nimmt. Das Attribut „schnell“ alleine reicht also nicht aus. Intelligenz ist
When I told a friend that the title of my new book is Simulating Data with SAS, she asked, “Why would anyone want to simulate data?” To her, data are measured or surveyed. Data tell us how big, how often, and how many. Data indicate people’s opinions about politics and
A SAS customer asks: How do I use SAS to generate multiple samples of size N from a multivariate normal distribution? Suppose that you want to simulate k samples (each with N observations) from a multivariate normal distribution with a given mean vector and covariance matrix. Because all of the
There is something for everyone at SAS Global Forum 2013. I like to attend presentations in the Statistics and Data Analysis track and talk with SAS customers in the SAS Support and Demo Area. But one activity that I enjoy the most is to stroll through the poster area and
For the fourth year, SAS is a sponsor of the National Online Teacher of the Year Award (NOTY), which recognizes an outstanding online teacher for exceptional quality in online K-12 education. Through education initiatives and innovative resources such as SAS Curriculum Pathways and SAS Mobile Education apps, SAS is a strong
Editor Len Tashman's Preview of Foresight Foresight has always presented its methods-based articles as either tutorials, which introduce and illustrate a methodology in nontechnical language, or as case studies, with a focus on the practical issues and challenges in generating forecasts. We lead off this issue with two practical issues articles. First, Stephan
A while ago I saw a blog post on how to simulate Bernoulli outcomes when the probability of generating a 1 (success) varies from observation to observation. I've done this often in SAS, both in the DATA step and in the SAS/IML language. For example, when simulating data that satisfied
I am pleased to announce that this year at SAS Global Forum 2013 (San Francisco, April 27 to May 1, 2013) I am giving a free hands-on workshop (HOW) entitled "Getting Started with the SAS/IML Language." If you are not familiar with the very popular Hands-On Workshop series at SAS
It's the start of a new year. Have you made a resolution to be a better data analyst? A better SAS statistical programmer? To learn more about multivariate statistics? What better way to start the New Year than to read (or re-read!) the top 12 articles for statistical programmers from
In a recent article on efficient simulation from a truncated distribution, I wrote some SAS/IML code that used the LOC function to find and exclude observations that satisfy some criterion. Some readers came up with an alternative algorithm that uses the REMOVE function instead of subscripts. I remarked in a
I recently encountered a SUGI30 paper by Chuck Kincaid entitled "Guidelines for Selecting the Covariance Structure in Mixed Model Analysis." I think Kincaid does a good job of describing some common covariance structures that are used in mixed models. One of the many uses for SAS/IML is as a language
There are a lot of useful probability distributions that are not featured in standard statistical textbooks. Some of them have distinctive names. In the past year I have had contact with SAS customers who use the Tweedie distribution, the slash distribution, and the PERT distribution. Often these distributions are used
It's not too early to think about what presentations and pre-conference training to attend while at SAS Global Forum 2012. Tutorials are an extra-fee that is only available as additions to a conference registration. But you can get a deal: Registration package 3 includes your choice of one Sunday Pre-Conference Tutorial.
Congratulations to all of these winners in the MWSUG Best Contibuted Papers! I hope you have all submitted your papers to the 2013 SAS Global Forum. The deadline for submissions ends soon! Here's a list that I know you have all been waiting for:
This weekend, lots of SAS authors are going to Las Vegas. The draw is the Analytics 2012 conference. There, several of our authors will lead discussions, including keynote speaker Tim Rey (coauthor of the new SAS Press book Applied Data Mining for Forecasting Using SAS) and Gerhard Svolba (author of
Right now, grid computing is one of the hottest topics here at SAS. To get more information about the technology and how people can get trained in it, I talked to Nancy Goodyear who manages e-Learning products at SAS. What is grid computing? Grid computing is a type of computing
I was recently flipping through Ross' Simulation (2006, 4th Edition) and saw the following exercise: Let N be the minimum number of draws from a uniform distribution [until the sum of the variates]exceeds 1. What is the expected value of N? Write a simulation to estimate the expected value. For
If you use a word three times, it's yours. -Unknown When I was a child, my mother used to encourage me to increase my vocabulary by saying, "If you use a word three times, it's yours for life." I believe that the same saying holds for programming techniques: Use a
This article is an excerpt from my forthcoming book Simulating Data with SAS. Not every matrix with 1 on the diagonal and off-diagonal elements in the range [–1, 1] is a valid correlation matrix. A correlation matrix has a special property known as positive semidefiniteness. All correlation matrices are positive
Math and analytics are back “in vogue,” says Kathy Lange, member of the Americas Business Analytics practice at SAS. Since she was little, Kathy has seen the world as one big math problem, and her devotion to mathematics is overwhelmingly clear in this lively interview. Read on below, and be
Christian Haxholdt, an analytics consultant in Global Professional Services and Delivery, has a passion for probability. Originally from Denmark, Christian is a former professor of statistics, and although he no longer teaches, he’s still an avid learner. Read on for his spirited interview, and be sure to check out the
A senior manager in the analytics product management group, Tonya Balan sees herself as a bridge between SAS customers and R&D, ensuring that SAS products stay relevant to the needs of the customer. With a background in statistics and experience as a college professor, Tonya shares her excellent advice and
This week's SAS tip comes from Peter Westfall, Randall Tobias, and Russell Wolfinger and their book Multiple Comparisons and Multiple Tests Using SAS, Second Edition. If you're interested in this topic, additional bonus content includes a free chapter from the book. The following excerpt is from SAS Press authors Peter Westfall, Randall Tobias,
I've been working on a new book about Simulating Data with SAS. In researching the chapter on simulation of multivariate data, I've noticed that the probability density function (PDF) of multivariate distributions is often specified in a matrix form. Consequently, the multivariate density can usually be computed by using the
We just published Gerhard Svolba’s Data Quality for Analytics Using SAS. When I first heard about it, I thought we’d have a tome covering such topics as standardizing data, cleaning it up, removing duplicates, and so on. However, as Gerhard says in his Introduction, “There are many aspects of data
Clarence So, Chief Strategy Officer for Salesforce.com, opened last month’s Chief Strategy Officer Summit in San Francisco (by the IE Group) with a challenging statement: ‘Your strategy is nothing more than the sum of your tactics’. I found this to be less than satisfactory as an explanation, but considering the
I've been a fan of statistical simulation and other kinds of computer experimentation for many years. For me, simulation is a good way to understand how the world of statistics works, and to formulate and test conjectures. Last week, while investigating the efficiency of the power method for finding dominant
