Questions tagged [sas]

SAS is a statistical software package. Use this tag for any on-topic question that (a) involves SAS either as a critical part of the question or expected answer, & (b) is not just about how to use SAS.

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14 views

In binary logistic regression, how do you interpret a categorical-by-categorical interaction term?

I am working with multiply imputed data and I have run a logistic regression model with 6 predictors (3 dichotomous and 3 categorical) and their interaction terms, controlling for a number relevant ...
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8 views

What is “categorical target variable” in SAS EM

"A categorical target variable that has exactly two categories (i.e., a binary or dichotomous variable)." What is "categorical target variable" in the SAS EM space? Is this ...
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1answer
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Why use a stratified log-rank test if we balance over strata anyway?

When comparing survival data over time, we can use the log-rank test. An extension of this is the stratified log-rank test, which adjusts for variables. Let's say we wanted to adjust for the effect of ...
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Sobel test for a mixed design experiment

Hi I have a mixed design experiment with 1 within subjects factor (4 levels) and 1 between subjects factor (4 levels). The following diagram shows a summary of the model that I am trying to test (...
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8 views

Pattern-mixture models in SAS

I've been asked to implement a pattern-mixture model using non-future dependent missing value restrictions (NFMV) as a sensitivity analysis for missing data. It appears as though SAS's PROC MI ...
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1answer
45 views

How to operationalize stratified, cluster survey sample “standard of the mean” in Excel

I have a question on the analysis of complex survey design. Basically, I am trying to replicate the SAS Surveymeans procedure in Excel in order to understand how to operationalize the equations to ...
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Tuning the Logit model based on sensitivity

I am working on a logistic model to predict whether or not an employee is likely to take a leave day during a given three month period. The model only correctly classified the “non-event" ...
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34 views

Interaction term with categorical predictors with more than one level

I am looking at the interaction between education (LTHS, HS, SOME COLLEGE, COLLEGE) and race (WHITE, BLACK, HISPANIC, ASIAN, NATIVE AMERICAN). I am using SAS and am including a class statement in my ...
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41 views

Post hoc test for Fisher's exact test (larger than 2x2)?

I have 2 categorical variables: Var1 - 3 levels, Var2- 5 levels (i.e., table is bigger than 2x2). I'm using SAS, and since I have multiple cells <5, I have run a Fisher's exact test with Monte ...
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Matching output from PROC glm in SAS to lme in the nlme package in R

I have a nested design with a fixed factor (Status) at the top. Nested in Status is Population, and nested in Population is Family. There are a few different responses I am fitting to this. In SAS, ...
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34 views

Lasso Application in SAS

I have a question regarding the Lassoapplication in SAS using cross validation method (choose =cvex and stop=none). I test different regression models and very often Lasso keeps all the variables such ...
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Understanding the Chi Squared test for Significance Analysis of Unobserved Components in SAS' Proc UCM

Proc UCM in SAS does a Chi Squared test to test the significance of the components found by fitting a UCM model. I want to understand what exactly this test is and how to interpret it. As in, what is ...
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Interaction term not significant but post-hoc tests are

I'm running a GEE model in SAS with an interaction term between two categorical variables group2 and lbl. Running a joint test, ...
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34 views

Can an odd ratio be as low as $< 0.001$?

With a 95% CI of $< 0.001$ to $> 999.999$? Any idea what could be wrong? (Sorry about the french output, will gladly provide more info if needed) Thanks a lot!
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out of sample prediction standard error and confidence limit using bootstrap

I am analyzing growth data to determine if sibling competition affect growth using GLIMMIX procedure in SAS with different class and continuous variables and 2 random effects. I want to predict out of ...
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Multiple imputation using proc mi EM method in SAS

I'd like to clarify how to use SAS for (multiple) imputation in SAS, specifically the EM method option for proc mi. Do I need to analyze multiple imputed sets using proc mianalyze as mentioned in ...
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1answer
82 views

Why does median() differ from quantile()[“50%”] in R and doesn't honor the type? Is this an estimator or sample quantile?

I just found, that when I want a specific type of quantile in R, say the number 3, it doesn't agree with median calculated in the "traditional way" in R. ...
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54 views

LASSO Regression with AIC or BIC as Model Selection Criterion

I am fitting a linear model using LASSO and exploring BIC (or AIC) as the selection criterion. The most useful resource I have stumbled upon is this earlier question here on CrossValidated: Is it ...
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77 views

Restricted Cubic Splines - Test Non-linearity in SAS

In SAS, I am having a very difficult time performing a formal test of non-linearity for the effect of one continuous variable estimated using restricted cubic splines. Yes, I know this is easy to ...
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19 views

Sample size for binary outcome and continuous (%) predictor

I have a project in which I have 60-70 samples. Outcome = binary (positive or negative case) Exposure = % of the time participants followed new guidelines (0-100%) Question - would it be correct to ...
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9 views

Logistic regression: How to generate Odds ratio table like in the image below

I am working on developing binaqry logistic regression model using SAS. I would like to generate the odds ratio and CI table like in the below image for the categorical variables. I am unable to ...
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Binary independent variables with missing values. Create dummy variables or not?

I am developing a prognostic model to predict an outcome. I have few binary variables with missing values, see below example. Is it better if I create dummy variables out of the below Gender variable ...
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Translate Mixed Models syntax from SAS to R (rewrite SAS proc mixed to R lmer)

Can anyone help me, please, to implement the SAS mixed model presented below in R lmer syntax? How to interpret such a model? <...
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Sas linear regression deciding on subgroups

I want to model the Total Volume as a function of the two variables Units and Price. I want to find out whether to model the total volume on the category as a whole or whether to model total volume by ...
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What type of statistical test should I perform?

What statistical technique would I need to carry out if I want to see if there is a significant differences in the number of units purchased when classifying observations based the variables Age, ...
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Comparing rates of hospital admissions or refusal rates year against year

I am trying to design a study for introducing a treatment and seeing if this would change rates of admission or leaving the hospital against medical advice. I would compare Jan-Dec 2020 (no tx offered)...
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SAS principal component analysis help [closed]

I have performed a principal component analysis on sas and have but my 15 variables into 4 factors so I have 4 new constructs. I now want to find out which of the original variables were important in ...
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Stationarity in SAS

I am reading the following page: https://documentation.sas.com/?cdcId=pgmsascdc&cdcVersion=9.4_3.4&docsetId=etsug&docsetTarget=etsug_arima_examples08.htm&locale=en I have a question: ...
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16 views

glmmTMB Kronecker direct product for crossed random effects

I am trying to replicate a model fit using SAS's Kronecker direct product covariance structure UN@AR(1) in glmmTMB. The model specification that I have currently is pretty close to SAS but something ...
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How to do covariate analysis in LTA and calculate p-values?

I am facing an issue in SAS when trying to do regression modelling using Proc LTA. I want to estimate odds ratios for transitional probabilities of 8 covariates. Although my model converges SAS is ...
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1answer
22 views

Identify individual networks within dataset containing many (using SAS preferably)

I have a dataset of links/edges that looks something like the following (except significantly larger - approx. 50,000 links): ...
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24 views

Change over time in QOL score

Hoping someone might help point me in the right direction with some questions I had (newby at stats, with 0 experience doing analysis with questionnaire data). Let’s say I have some participants who ...
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1answer
162 views

Why do the coefficients of cross-sectional fixed effects and time fixed effects become zero?

I currently have a panel data set that contains the quarterly increment of loans initiated from more than 300 cities in China over the period from 2011Q1 to 2020Q2. I want to examine the impact of ...
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1answer
60 views

Mixed model effects - can the results in this paper be correct?

I've read the following paper about recall rates for information being higher when said information is supplemented with pictographs: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2656019/ and am a bit ...
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Comparing Blood pressure control and stroke within ethnic groups and between them

I was wondering if people would know what test to use. Using NHANES data, what are the BP control (proportion at <140 SBP and <90 DBP) rates according to presence vs. absence of self-reported ...
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125 views

Could anyone verify the MMRM model implemented in R with SAS against the estimates and degrees of freedom?

I'm trying to find out if the gls() procedure in R is equivalent to the REPEAT statement in SAS procedure for mixed models. In other words, I would like to check if R is able to run the MMRM model. ...
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28 views

Causal Mediation for Survival Analysis: Help with Popular SAS Macro

I am attempting a simple mediation analysis in a Cox model using a popular SAS Macro as described by here Importantly, the description of the macro is also given at https://cdn-links.lww.com/permalink/...
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Interpreting SAS output - Roots of AR Characteristic Polynomial

I urgently need help on interpreting the numbers from a SAS output on Characteristic Roots: The VARMAX Procedure The VARMAX Procedure Roots of AR Characteristic Polynomial Index Real Imaginary Modulus ...
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1answer
39 views

Constraining a parameter in a 4 level variable In a propensity score regression

I’m generating a propensity score using logistic regression in SAS. The model predicts compliance with a quality measure. I will match patients into groups who actually complied and not complied with ...
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1answer
16 views

PLS procedure in SAS software

experts, I have a question about PLS procedure in SAS. The manual said that the prediction on new data is by combining training data and new data (new data dont have response values). I did ...
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307 views

Interaction with restricted cubic spline - comparison between SAS and R

When performing the same cox-regression in SAS and i R (including and interaction with a 3 knot restricted cubic spline), I receive different parameter estimates (i.e on age_spline 2). In my example ...
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2answers
229 views

Compare regression coefficients within the same model

I ran a regression model with around 10 regression coefficients. I now want to test wether these regression coefficients are significantly different from one another. How do I do this? Is a Wald test ...
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Logistic regression with small and differing sample sizes

I asked this question on Stack Overflow and was encouraged to come here for more help regarding methodological limitations. Previous question: I ran the model in SAS and I can't make sense of the ...
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13 views

How does partial least squares algorithm return more than one factor?

My understanding of PLS regression is that we find an eigen vector such that it maximises the covariance between X(matrix of independent variables) and Y(vector/matrix of dependent variable) i.e. find ...
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17 views

What are the most likely reasons for convergence failure in back-fitting algorithm (GAM)?

I'm trying to build a binomial model using proc gam in SAS. When I include certain predictors as splines in the model , I get an error that the scoring algorithm ...
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24 views

Submitting Lasso Results For Publication

I am creating a model to predict cost of a particular surgery. I have n = ~20,000 and have >300 variables to choose from. I decided to use a 5 fold cross validation Lasso approach in SAS (proc ...
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22 views

Should I use fixed or random effects?

I have a healthcare data set with one (six meter walk test) and two predictors (baseline six meter walk test as a covariate, and days of treatment). We want to know if 6MWT improves over time (using ...
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24 views

Including all treatments in crossover design mixed model in SAS

I have a dataset effects of 3 treatments against ctrl on cell-lines collected from 4 donors. ...
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Validity of setting Singular=1 in proc GLM Contrast statement (SAS)

I am running a proc GLM in SAS with specific contrasts, one of which is included in the code below. With the following code, all my contrasts are always unestimable: ...
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1answer
55 views

logistic mixed model very large standard error

I'm running a logistic mixed model (in SAS) and these are my results: ...

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