A previous article provides an example of using the BOOTSTRAP statement in PROC TTEST to compute bootstrap estimates of statistics in a two-sample t test. The BOOTSTRAP statement is new in SAS/STAT 14.3 (SAS 9.4M5). However, you can perform the same bootstrap analysis in earlier releases of SAS by using
We have updated our software for improved interpretability since this post was written. For the latest on this topic, read our new series on model-agnostic interpretability. Assessing a model`s accuracy usually is not enough for a data scientist who wants to know more about how a model is working. Often
The SURVEYSELECT procedure in SAS 9.4M5 supports the OUTRANDOM option, which causes the selected items in a simple random sample to be randomly permuted after they are selected. This article describes several statistical tasks that benefit from this option, including simulating card games, randomly permuting observations in a DATA step,
The SAS language provides syntax that enables you to quickly specify a list of variables. SAS statements that accept variable lists include the KEEP and DROP statements, the ARRAY statement, and the OF operator for comma-separated arguments to some functions. You can also use variable lists on the VAR statements
In my article about how to construct calibration plots for logistic regression models in SAS, I mentioned that there are several popular variations of the calibration plot. The previous article showed how to construct a loess-based calibration curve. Austin and Steyerberg (2013) recommend the loess-based curve on the basis of
A logistic regression model is a way to predict the probability of a binary response based on values of explanatory variables. It is important to be able to assess the accuracy of a predictive model. This article shows how to construct a calibration plot in SAS. A calibration plot is
In a previous blog post, I discussed ways to produce statistically independent samples from a random number generator (RNG). The best way is to generate all samples from one stream. However, if your program uses two or more SAS DATA steps to simulate the data, you cannot use the same
Simulation studies require both randomness and reproducibility, two qualities that are sometimes at odds with each other. A Monte Carlo simulation might need to generate millions of random samples, where each sample contains dozens of continuous variables and many thousands of observations. In simulation studies, the researcher wants each sample
SAS programmers on SAS discussion forums sometimes ask how to run thousands of regressions of the form Y = B0 + B1*X_i, where i=1,2,.... A similar question asks how to solve thousands of regressions of the form Y_i = B0 + B1*X for thousands of response variables. I have previously
Inspired by curiosity and backed by the most powerful analytics in the world, SAS discovers a new planet in our Solar system. See how we used SAS Viya to make this historic discovery.
EBA-Stresstest, TRIM-Initiative – es gibt 2018 mehr denn je dringende Gründe für die Banken, sich konsequent datenorientiert und analytisch aufzustellen und so vom Gejagten der Aufsicht zum Jäger nach mehr Wertschöpfung zu werden. Alle Banken wissen das. Die schlechte Nachricht: Die wenigsten Institute widmen sich diesem Thema ohne Wenn und
Many people know that a surface can contain a saddle point, but did you know that you can define the saddle point of a matrix? Saddle points in matrices are somewhat rare, which means that if you choose a random matrix you are unlikely to choose one that has a
When I first learned to program in SAS, I remember being confused about the difference between CLASS statements and BY statements. A novice SAS programmer recently asked when to use one instead of the other, so this article explains the difference between the CLASS statement and BY variables in SAS
If N random people are in a room, the classical birthday problem provides the probability that at least two people share a birthday. The birthday problem does not consider how many birthdays are in common. However, a generalization (sometimes called the Multiple-Birthday Problem) examines the distribution of the number of
This article simulates the birthday-matching problem in SAS. The birthday-matching problem (also called the birthday problem or birthday paradox) answers the following question: "if there are N people in a room, what is the probability that at least two people share a birthday?" The birthday problem is famous because the
What is a random number generator? What are the random-number generators in SAS, and how can you use them to generate random numbers from probability distributions? In SAS 9.4M5, you can use the STREAMINIT function to select from eight random-number generators (RNGs), including five new RNGs. After choosing an RNG,
Wherever there is uncertainty there has got to be judgment, and wherever there is judgment there is an opportunity for human fallibility. Donald Redelmeirer, physician-researcher Recently, I read a fascinating book titled The Undoing Project: A Friendship That Changed Our Mind by Michael Lewis (W.W. Norton & Company, 2017). Lewis
Last week I got the following message: Dear Rick: How can I create a normal distribution within a specified range (min and max)? I need to simulate a normal distribution that fits within a specified range. I realize that a normal distribution is by definition infinite... Are there any alternatives,
I wrote more than 100 posts for The DO Loop blog in 2017. The most popular articles were about SAS programming tips, statistical data analysis, and simulation and bootstrap methods. Here are the most popular articles from 2017 in each category. General SAS programming techniques INTCK and INTNX: Do you
Regulierung, Kostendruck und technologische Weiterentwicklung – ist abwarten und Tee trinken die bessere Strategie für die Banken, als die Ärmel hochzukrempeln und loszulegen, nur, weil die Regulierung mal wieder hustet? Wie gehen Institute mit den immerwährenden neuen Regulierungen um? Wie sieht es in der Praxis aus, sind Basel, IFRS oder
In meinen ersten drei Blogs (1/2/3)habe ich Ihnen eine Bauanleitung vorgestellt, mit der Sie Edge Analytics in einen Modell-Truck im Maßstab 1:14 montieren können. Das schien wie eine Spielerei, hat aber sehr reale Anwendungsszenarien. Heute, in Teil 4, möchte ich Sie zu einer eleganten Rolle rückwärts einladen! Will sagen: Die
Happy holidays to all my readers! My greeting-card to you is an image of a self-similar Christmas tree. The image (click to enlarge) was created in SAS by using two features that I blog about regularly: matrix computations and ODS statistical graphics. Self-similarity in Kronecker products I have previously shown
When you run an optimization, it is often not clear how to provide the optimization algorithm with an initial guess for the parameters. A good guess converges quickly to the optimal solution whereas a bad guess might diverge or require many iterations to converge. Many people use a default value
This article shows how to simulate beta-binomial data in SAS and how to compute the density function (PDF). The beta-binomial distribution is a discrete compound distribution. The "binomial" part of the name means that the discrete random variable X follows a binomial distribution with parameters N (number of trials) and
„… Internet, Internet, ich hör‘ hier immer Internet. Sag’n Se‘ ma‘, ganz richtig ist das nicht!“ Der Service-Manager errötet nach seinem Rap. Lenin schwankt zwischen Belustigung und bolschewistischem Ingrimm: Stellt der Rote Rapper seine Erfolge im Internet of Things infrage? Der Rapper fährt fort: „Denn diese Daten, die Sie verbraten,
Dementia describes different brain disorders that trigger a loss of brain function. These conditions are all usually progressive and eventually severe. Alzheimer's disease is the most common type of dementia, affecting 62 percent of those diagnosed. Other types of dementia include; vascular dementia affecting 17 percent of those diagnosed, mixed
The article "Fisher's transformation of the correlation coefficient" featured a Monte Carlo simulation that generated sample correlations from bivariate normal data. The simulation used three steps: Simulate B samples of size N from a bivariate normal distribution with correlation ρ. Use PROC CORR to compute the sample correlation matrix for
I sit here fascinated, watching a world population clock. According to the US Census, a baby is born and a person dies every 7 and 12 seconds, respectively, in the United States. In 1950 our world had about 2.5 billion people; currently our population is over 7.3 billion. Estimates predict
My article about Fisher's transformation of the Pearson correlation contained a simulation. The simulation uses the RANDNORMAL function in SAS/IML software to simulate multivariate normal data. If you are a SAS programmer who does not have access to SAS/IML software, you can use the SIMNORMAL procedure in SAS/STAT software to
ODER: Wie erstelle ich ein Edge Analytics Case auf Basis von SAS ESP, SAS Streamviewer und eines Modelltrucks? Das beschreibe ich in Teil 3. Rückblick: Im ersten Teil wurden die Idee und der Inhalt der SAS Streaming-Analytics-Demo beschrieben. Im zweiten Teil sind die einzelnen technischen Komponenten sowie die Software aufgelistet. Im
