# Tagged Questions

SAS is a proprietary cross-platform general-purpose statistical software package. [Official Website](http://www.sas.com/index.html)

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### Restricting model parameters in logistic models in R

Is there any function in R that can solve the problem like this example from the SAS website: Beginning in SAS 9.3, PROC FMM can be used as an alternative to ...
330 views

### Reporting predicted outcome of mixed effects models

I am analyzing some group-randomized longitudinal trial data with three time points using mixed effects model. Some people missed 1-2 time points, and I didn't exclude any cases with missing dependent ...
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### SAS and Principal Components Analysis

I'm new to SAS coding from SPSS point and click. I don't currently have SPSS, so SAS is my only option. My question is: how do I get the percent variance explained and cumulative variance explained ...
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### Avoiding the Generalized Variance Formula for the NYC Housing and Vacancy Survey

I am attempting to devise a replication-based survey design that closely replicates a taylor-series design used by the US Government publication - where I do not have access to all of the ...
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### How big of a dataset can R or SAS handle for regression?

On a standard computer (~3-6gb RAM) with 2 - 4 processors. What are the size restrictions on a matrix of data for R or SAS?
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### Are GAMMs/GLM the best choice for calculating number of germs on hands?

We would like your opinion on whether GAMMs are a good option and how best to go about implementing for the following: During a period of patient care, a nurse will accrue $Y$ colonies of bacteria on ...
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### Estimating Smoothing Parameters Simultaneously with Regression Coeffecients

I am developing a forecasting model that relies on a smoothed leading indicator. The indicator is the ratio of two smoothed series, and the forecasting regression equation uses a lagged value of the ...
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### What is the difference between estimate and contrasts in SAS?

I am having difficulty determining the difference between the two statements.
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### Degrees of freedom for mixed model

Using data and code the example from http://www.ats.ucla.edu/stat/sas/faq/anovmix1.htm: ...
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### R as an alternative to SAS for large data

I know that R is not particularly helpful for analysing large datasets given that R loads all the data in memory whereas something like SAS does sequential analysis. That said, there are packages like ...
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### What is the Survival Function using SAS LIFEREG with lognormal distribution?

I am trying to plot the survival curve using output from PROC LIFEREG with a lognormal distribution. Is my formula for the survival function (prob[i], where i is time) correct? Below is my SAS code. ...
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### Profile likelihood confidence intervals

The theory behind profile likelihood (PL) confidence intervals (CIs) is clear to me. (See here, for example). SAS is surprisingly quick in calculating the PL CIs for all the covariates in a given ...
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### Backward selection in a Cox regression model

My goal is to fit a cox regression model in SAS, for which I use the PROC PHREG statement. As I am still new to regression methods, I would appreciate a little of ...
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### Media or market mix modeling?

Can anyone tell me how to build media mix model? Is it similar to market mix model? What are the steps and variables in the model? If I want to build in SAS which procedure should I use?
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### Which are the correct sum of squares for repeated measures ? (balanced example)

Below are three ways to fit a MANOVA model in R and to extract ANOVA tables from the fitted model. The design is balanced. All methods give different results. The data are 5 groups of 4 individuals ...
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### using a number of variables (dummy) in mixed model analysis in R

I have following type of data: ...
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### How to generate the time series from a given model?

we consider a sparse autoregressive time series of length 1000 obeying the model X(t)=0.2X(t-1)+0.1X(t-3)+0.2X(t-5)+0.3X(t-10)+0.1X(t-15)+Z（t） with nonzero coefficients at lags 1,3,5,10 and 15,where ...
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### Experimental design & model

I'm testing the effect of land history and soil organisms on the growth of Stinging nettle. To investigate the effect of land history ("hist") on growth, soil samples ("sample") were collected at 10 ...
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### Pre-Post analysis with repeated measure

I've 50 subjects and ran an experiement 4 times for each subject and collected the pre and post vlaues for each run. I need to do pre post analysis. Here a sample of my data: ...
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### Frequency Table for Repeated Measures

I've 12 unique subjects, and in total I've almost 1700 observations. I've an ordinal response variable (has 4 levels) and 3 categorical covariates (each one has different levels 3, 5, 2, and 4 ...
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### Results from multinomial ordinal logistic regression model

I've an ordinal response variable (has 4 levels) and 3 categorical covariates (each one has different levels 3, 5, 2, and 4 respectively). We also are dealing with repeated observations. I fitted a ...
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### How do I get individual values of the random effect intercept in SPSS?

I am implementing a random intercept model in SPSS, and would like to obtain the subject-specific values of the random intercept to test it for normality. Does anyone know what's the SAS equivalent of ...
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### SAS error: variance covariance matrix singular

I am now working with a classmate on an estimate of an Almost Ideal Demand System for tobacco consumption. We have chosen to make an AIDS regression using goods tobacco and alchol, and the CPI price ...
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### Getting the good prediction standard error with R and/or SAS

Consider for instance the balanced one-way random effects ANOVA model: (y_{ij} \mid \mu_i) \sim_{\text{iid}} {\cal N}(\mu_i, \sigma^2_w), \quad j=1,\ldots,J, \qquad \mu_i \sim {\cal N}(\mu, ...
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### Repeated measure problem (Discrete variables) [duplicate]

Possible Duplicate: Difference between generalized linear models & generalized linear mixed models in SPSS Repeated measure problem I have 6 subjects. For each subject, we measured ...
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### Repeated measure problem

I have 6 subjects. For each subject, we measured two variables over six-week period once a week. Let’s call the variables A and B. Variable A is binary (male or female), and variable B is continuous ...
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### Interpretation of sas output of survival Frailty model using Proc NLMIXED

I am new to the site, I am trying to fit a Weibull gamma frailty model in SAS for multiple event times per subject, using proc nlmixed procedure. Please how do I ...
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### How to preform 1NN with single centroid per class in SAS?

I've computer a single centroid per class using PROC fastclus in SAS, ...
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### Model reduction - Backward elimination

The rule I use for reducing covariates (trimming) is as following: Look at the highest order interaction. If that is not significant, drop it. If it is significant, stop. If drop the highest order ...
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### How to specify in r spatial covariance structure similar to SAS sp(pow) in a marginal model?

I'm currently translating existing code from SAS to R. I'm working on longitudinal data (CD4 count over time). I have the following SAS code : ...
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### Interpretation of ordinal logistic regression output from SAS

In the SAS output for ordinal logistic regression, how should "Assessment Score Rankings" and "Assessment Score Distribution" tables be interpreted?
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### Covariate in generalized linear model with binary DV

I am comparing an offender group with a control group on a certain task in a generalized linear model with accuracy (0-1) as the DV. The reviewers criticized me by mentioning that one group was ...
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### How to get correct Covariance components in SAS Proc mixed? Struggling with infinite likelihoods and negative variance components

I am trying to estimate covariance components from PROC MIXED and having trouble with convergence problems in the REML approach when I use the NOBOUNDS option. Let me explain why I am using NOBOUNDS ...
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### Prediction model problem

I am trying to design a model that can estimate the number of customers I will receive in every store every month using the number of customers I received every month in every store for the last five ...
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I'm working on a robust regression analysis with SAS. I'm running a full model first.(using PROC ROBUSTREG). Then I'm excluding ...
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### What is the best source to start learning SAS?

I'm looking for some book recommendations, video lectures, tutorials or anything that can help me learn SAS.
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### Logistic Regression - Predicting an event with a couple time-related issues

I'm using logistic regression to predict the occurrence of tree carcasses falling after a mortality event. Data include a variety of topographic and tree characteristic variables and also time since ...
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### Mixed model runs well in R whereas a random effect has only one level

How do you explain that ? There's only one operator but the mixed model returns an estimate for the operator random effect. Furthermore the ...
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### When the response variable is a proportion (r/n) in proc logistic, how to express the model in terms of $\pi, \alpha, \beta$?

A (SAS documentation file) (page 1906) on "The LOGISTIC Procedure" gives the following procedure- proc logistic; model r/n=x1 x2; run; Here, n represents the ...
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### How to calculate 95% CI for OR for a different reference category without running the SAS logistics again?

My question is about calculation of confidence interval (CI) for odds ratio (OR) from a SAS output of a logistic regression model for a different reference category without running the SAS program ...
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### Non-parametric for two-way ANOVA (3x3)

My dependent variable is continuous, non-normal (skewed left according to Shapiro-Wilk test). I have two independent variables (treatment group by colour, food type). There are 3 levels within each ...
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### prediction interval for heteroscedastic data

Here are some data: ...
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### Sum of Squares reduction test: Convergence criteria met, but not all parameters of the model estimated

Background: I am using weighted non-linear regression to model the growth of plant organs, with dummy variables for different species. I am using a sum of squares reduction test (SSRT) to compare the ...
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### Panel data: Logistic fixed-effect model with a non-varying / constant dependent variable

As a part of my master’s thesis, I am currently undertaking a statistical analysis of corporate turnaround. I have a panel dataset consisting of approximately 200 firms for 6 years each gathered ...
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### Degrees of freedom in my mixed model

I am having a serious issue trying to figure out why my degrees of freedom are screwy when running my proc mixed model. I have nested data for a MLM analyses, but SAS isn't providing the correct df ...
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### Predicting a time-series based on level, season, and cycle

I have time-series data for stock price. A sample of dataset is given below: ...
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### How far in future is call center workload accurate

I am working on call center load forecasting. I have daily call volume for past 24 months along with few variables which does affect call load. Though none of these variables have come significant in ...
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### How do I interpret this McNemar's agreement plot generated by SAS?

I'm running a simple McNemar's test for agreement on the McNemar's example from Wikipedia. The test uses the following data: for patients of Hodgkin's disease. Running this SAS code: ...