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Data Visualization | Learn SAS | Programming Tips

Rick WicklinSeptember 18, 2023 0

Use PROC SGPLOT to embed a graph inside another graph

Did you know that you can embed one graph inside another by using PROC SGPLOT in SAS? A typical example is shown to the right. The large graph shows kernel density estimates for the distribution of the Cholesterol variable among male and female patients in a heart study. The small

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Advanced Analytics | Analytics | Learn SAS | Work & Life at SAS

Adriana RojasSeptember 13, 2023 0

Colaboración entre universidades y empresas: intercambio mutuo de conocimiento

No creo que ninguno de los lectores de este post llegue a sorprenderse si les contamos que en SAS estamos al 100% comprometidos con el mundo académico. No obstante, hace casi medio siglo que nuestra compañía nació precisamente en las aulas de una universidad, la de Carolina del Norte. Desde

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SAS Spain | Spanish

Learn SAS | Programming Tips

Rick WicklinSeptember 13, 2023 0

The SG annotation macros in SAS

I don't often use the SG annotation facility in SAS for adding annotations to statistical graphics, but when I do, I enjoy the convenience of the SG annotation macros. I can never remember the details of the SG annotation commands, but I know that the SG annotation macros will create

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Learn SAS | Programming Tips

Rick WicklinSeptember 11, 2023 0

On the performance of BY-group processing in SAS IML

Many SAS procedures support a BY statement that enables you to perform an analysis for each unique value of a BY-group variable. The SAS IML language does not support a BY statement, but you can program a loop that iterates over all BY groups. You can emulate BY-group processing by

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Analytics | Learn SAS

5 claves para crear equipos de analítica más sólidos

Catherine (Cat) Truxillo

Catherine (Cat) TruxilloSeptember 7, 2023 0

5 claves para crear equipos de analítica más sólidos

Debido a la complejidad y cambios en el mercado, las organizaciones de todo el mundo están aprovechando las oportunidades para hacer mejores predicciones, identificar soluciones y dar pasos estratégicos y proactivos, lo que significa que dependen cada vez más de los big data. Sin embargo, en su búsqueda de resistencia

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Banking | Communications | Education | Energy & Utilities | Government | Health Care | Hospitality | Insurance | Life Sciences | Manufacturing | Retail | Sports & Entertainment | Travel

Analytics | Learn SAS | Programming Tips

Rick WicklinSeptember 6, 2023 0

Model data from published summary statistics

There are many ways to model a set of raw data by using a continuous probability distribution. It can be challenging, however, to choose the distribution that best models the data. Are the data normal? Lognormal? Is there a theoretical reason to prefer one distribution over another? The SAS has

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Learn SAS | Programming Tips

Rick WicklinAugust 30, 2023 0

Simulate the use of personal checks in the US

Does anyone write paper checks anymore? According to researchers at the Federal Reserve Bank of Atlanta (Greene, et al., 2020), the use of paper checks has declined 63% among US consumers since the year 2000. The researchers surveyed more than 3,000 consumers in 2017-2018 and discovered that only 7% of

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Advanced Analytics | Analytics | Data Management | Learn SAS | Programming Tips

Yinliang WuAugust 29, 2023 0

How to evaluate SAS expressions in PROC DS2 dynamically

Some readers read the article “how-to-evaluate-sas-expression-in-data-step-dynamically” and wonder if there is a same mechanism or functionality in DS2. As indicated in that article, SAS provides similar features in DATA step, PROC CAS and PROC Python, but some projects like ESP (Event Stream Processing) projects would store those expression definition in

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Analytics | Learn SAS

Rick WicklinAugust 23, 2023 0

Bootstrap predicted means by using PROC GLMSELECT

A previous article shows how to use the MODELAVERAGE statement in PROC GLMSELECT in SAS to perform a basic bootstrap analysis of the regression coefficients and fit statistics. A colleague asked whether PROC GLMSELECT can construct bootstrap confidence intervals for the predicted mean in a regression model, as described in

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Analytics | Learn SAS

Rick WicklinAugust 21, 2023 0

A simple way to bootstrap linear regression models in SAS

I've written many articles about bootstrapping in SAS, including several about bootstrapping in regression models. Many of the articles use a very general bootstrap method that can bootstrap almost any statistic that SAS can compute. The method uses PROC SURVEYSELECT to generate B bootstrap samples from the data, uses the

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Learn SAS | Programming Tips

Rick WicklinAugust 16, 2023 0

Add Unicode symbols and format text labels in SAS

It has been more than a decade since SAS 9.3 changed the default ODS destination from the old LISTING destination to more modern destinations such as HTML. One of the advantages of modern output destinations is support for Unicode symbols, superscripts, subscripts, and for formatting text by using boldface, italics,

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Analytics | Learn SAS | Programming Tips

Rick WicklinAugust 14, 2023 0

Bootstrap confidence intervals for the predicted mean in a regression model

In ordinary least squares regression, there is an explicit formula for the confidence limit of the predicted mean. That is, for any observed value of the explanatory variables, you can create a 95% confidence interval (CI) for the predicted response. This formula assumes that the model is correctly specified and

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Learn SAS | Programming Tips

Rick WicklinAugust 9, 2023 0

Plot confidence intervals for a regression model in SAS

A SAS programmer wanted to use PROC SGPLOT in SAS to visualize a regression model. The programmer wanted to visualize confidence limits for the predicted mean at certain values of the explanatory variable. This article shows two options for adding confidence limits to a scatter plot. You can use a

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Learn SAS | Programming Tips

Rick WicklinAugust 7, 2023 0

Construct an envelope function for the acceptance-rejection method

The acceptance-rejection method (sometimes called rejection sampling) is a method that enables you to generate a random sample from an arbitrary distribution by using only the probability density function (PDF). This is in contrast to the inverse CDF method, which uses the cumulative distribution function (CDF) to generate a random

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Analytics | Learn SAS | Programming Tips

Noah HanJuly 31, 2023 0

SoDA 서비스 가입하기

SoDA를 이용해 쉽게 배우는 데이터 과학 #2 지난 포스팅에서는 SoDA(SAS Ondemand for Academics)의 장점과 필요성을 중심으로 SoDA가 어떤 제품인지 소개해 드렸습니다. 이번 포스팅에서는 ‘서비스 가입 방법’을 알아보겠습니다. 먼저 SoDA가 서비스 되는 브라우저 환경을 알아보고, 이어서 서비스 가입의 각 단계를 살펴보겠습니다. * 편집자 주 : 이번 글은 SAS코리아 컨설팅 본부 한노아

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Learn SAS | Programming Tips

Rick WicklinJuly 31, 2023 0

Create a probability distribution from almost any positive function

There are dozens of common probability distributions for a continuous univariate random variable. Familiar examples include the normal, exponential, uniform, gamma, and beta distributions. Where did these distributions come from? Well, some mathematician needed a model for a stochastic process and wrote down the equation for the distribution, typically by

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Analytics | Learn SAS | Programming Tips

Rick WicklinJuly 19, 2023 0

On the computation of the Wilcoxon signed rank statistic

Wilcoxon's signed rank test is a popular nonparametric alternative to a paired t test. In a paired t test, you analyze measurements for subjects before and after some treatment or intervention. You analyze the difference in the measurements for each subject, and test whether the mean difference is significantly different

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Analytics | Learn SAS

Rick WicklinJuly 17, 2023 0

Standardize regression coefficients for models that include categorical variables

A previous article discusses standardized coefficients in linear regression models and shows how to compute standardized regression coefficients in SAS by using the STB option on the MODEL statement in PROC REG. It also discusses how to interpret a standardized regression coefficient. Recently, a SAS user wanted to know how

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Learn SAS | Programming Tips

Rick WicklinJuly 10, 2023 0

Simulate from a Markov model

A previous article shows an example of a Markov chain model and computes the probability that the system ends up in a terminal state (called an absorbing state). As explained previously, you can often compute exact probabilities for questions about Markov chains. Nevertheless, it can be useful to know how

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Learn SAS | Programming Tips

Rick WicklinJuly 5, 2023 0

The probability of reaching a terminal state in a Markov chain

A previous article shows how to model the probabilities in a discrete-time Markov chain by using a Markov transition matrix. A Markov chain is a discrete-time stochastic process for which the current state of the system determines the probability of the next state. In this process, the probabilities for transitioning

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Analytics | Learn SAS | Programming Tips

Rick WicklinJune 28, 2023 0

Compute the geometric median in SAS

Given a set of N points in k-dimensional space, can you find the location that minimizes the sum of the distances to the points? The location that minimizes the distances is called the geometric median of the points. For univariate data, the "points" are merely a set of numbers $${p_1,

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Analytics | Learn SAS

Rick WicklinJune 26, 2023 0

Compute the geometric median of a triangle

While writing an article about labeling a polygon by using the centroid, I almost made a false claim about the centroid. I almost claimed that that the centroid is the point in a polygon that minimizes the sum of the distances to the vertices. It is not. The point that

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Analytics | Learn SAS

Rick WicklinJune 21, 2023 0

Barycentric coordinates for a triangle

A colleague asked how to compute the barycentric coordinates of a point inside a triangle. Given a triangle in the plane with vertices p1, p2, and p3, every point in the triangle can be represented as a convex combination of the vertices: c1*p1 + c2*p2 + c3*p3, where c1,c2,c3 ≥

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Learn SAS | Programming Tips

Rick WicklinJune 19, 2023 0

Use built-in ODS templates to display SAS tables

Part of the power of the SAS ODS system is the ability to visualize data by using ODS templates. An ODS template describes how to render data as a table or as a graph. A lot of papers and documentation have been written about how to define a custom template

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Learn SAS | Programming Tips

Rick WicklinJune 14, 2023 0

Eigenvalues of a tridiagonal Toeplitz matrix

While writing an article about Toeplitz matrices, I saw an interesting fact about the eigenvalues of tridiagonal Toeplitz matrices on Nick Higham's blog. Recall that a Toeplitz matrix is a banded matrix that is constant along each diagonal. A tridiagonal Toeplitz matrix is zero except for the main diagonal, the

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Learn SAS | Programming Tips

Rick WicklinJune 12, 2023 0

How to construct an unsymmetric Toeplitz matrix

A Toeplitz matrix is a banded matrix. You can construct it by specifying the parameters that are constant along each diagonal, including sub- and super-diagonals. For a square N x N matrix, there is one main diagonal, N-1 sub-diagonals, and N-1 super-diagonals, for a total of 2N-1 parameters. In statistics and applied

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Analytics | Learn SAS | Programming Tips

Noah HanJune 7, 2023 0

SoDA로 데이터 과학 시작하기

SoDA를 이용해 쉽게 배우는 데이터 과학 #1 SoDA(SAS OnDemand for Academics)는 SAS가 무료로 제공하는 교육용 데이터 분석 소프트웨어 프로그램입니다. 앞으로 4회에 걸쳐 'SoDA 를 이용해 쉽게 배우는 데이터 과학'을 자세히 소개해 드리도록 하겠습니다. SoDA란? SoDA (SAS OnDemand for Academics; SoDA)는 데이터 과학을 처음 배우는 입문자들에게 SAS를 무료로 배울 수 있도록

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Analytics | Learn SAS

Rick WicklinJune 7, 2023 0

Visualize the Spearman rank correlation

A previous article explains the Spearman rank correlation, which is a robust cousin to the more familiar Pearson correlation. I've also discussed why you might want to use rank correlation, and how to interpret the strength of a rank correlation. This article gives a short example that helps you to

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Learn SAS

Rick WicklinJune 5, 2023 0

Moire patterns: Or why you shouldn't wear a striped shirt on a video

Since the COVID-19 pandemic began, video presentations and webcasts have become a regular routine for many of us. On days that I will be using my webcam, I wear a solid-color shirt. If I don't plan to be on camera, I can wear a pinstripe Oxford shirt. Why the difference?

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Data Visualization | Learn SAS

Rick WicklinMay 30, 2023 0

How to use a log-scale on a histogram

Real-world data often exhibits extreme skewness. It is not unusual to have data span many orders of magnitude. Classic examples are the distributions of incomes (impoverished and billionaires) and population sizes (small countries and populous nations). The readership of books and blog posts show a similar distribution, which is sometimes

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