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

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Performing PCA on a tetrachoric matrix in SPSS

I am currently working on a project where I have nine dependent variables, each binary, measuring similar outcomes. Accordingly, I'd like to perform a principal component analysis on them to reduce ...
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32 views

Slight difference in output of SAS proc genmod and R glm

I am trying to reproduce a model fit using SAS proc genmod in R glm and am able to get the same estimates and SE's for all parameters except the intercept and Distance coefficient. SAS: ...
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16 views

Vif and stepwise regression

I used the VIF to detect multicollinearity, I want to use forward selection and backward elimination procedures. My question is: Do I have to use all the variables in my dataset in the procedures or ...
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12 views

Modeling farm socio/demographics to determine influence on net income

I am attempting to isolate the effect on net income of incorporating a certain type of marketing strategy for farms. My initial OLS model produced positive and expected results, but when I graphed my ...
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12 views

SCCS (Self Controlled Case Series) with SAS - How to consider continuous expositions?

I have a question about the SCCS (self-controlled case series) method (I use SAS, but whatever). I understand how to deal with it when there are ponctual expositions (like vaccins) followed by fixed ...
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1answer
25 views

SAS PROC MIXED Parameter Interpretation

I have a dataset and am attempting to run proc mixed with the intent of collecting parameter estimates for future projections. I am interested in how Y changes with X1, over various locations. I am ...
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1answer
22 views

How to interpret AR(1) parameter estimates from SAS time series forecasting system?

I am attempting to fit an AR(1) model to some synthetic data, to become more familiar with the time series forecasting system in SAS. In my understanding, such a model would be of the form X(t) = c + ...
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29 views

Poor survival analysis model fit with Gronnesby and Borgan

I have been experiencing issues with model fit. In my example, I have set up a time-varying (counting method) survival analysis model (Cox regression with ...
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13 views

PCA scores from SAS (what's going on in the background) [duplicate]

I'm having a hard time explaining what's going on in the background (stats) when SAS creates component scores after running a PCA. I understand that the default method for SAS component scores is the ...
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12 views

Writing code for Generalised nonlinear mixed effect model in WinBUGS/JAGS [migrated]

For my research purpose, I need to do Generalised nonlinear mixed effect model to analyse some repeated measure count data. I have some tree mortality data from 1950 which were measure in different ...
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9 views

Discrepancy in odds ratios when using dummy and effect coding - which is better?

I have a binary outcome variable and several binary predictor variables. When performing a logistic regression (proc logistic) in SAS, I get different odds ratios ...
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1answer
38 views

Split-plot analysis with four factors in SAS

I'm trying to correctly model a split-plot design with more than two factors (specifically, four) in SAS. I'm interested in an example from Design and Analysis of Experiments (Montgomery , 8th Ed.), ...
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62 views

Daily data forecast: How to specify day of week and month of the year seasonality in SAS

I have daily data for 2 years starting from jan1 2014 till december 31 2015. I want to forecast for next 365 days using this data set. I am using below code. ...
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20 views

heteroscedastic time series in SAS autoreg - white noise matter?

I normally work with categorical outcomes, so a lot of this is new to me. Attempting to model monthly interrupted time-series in proc autoreg. There were 11 intervention changes of varying potency ...
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1answer
47 views

SAS dataset (for beginner) [closed]

proc lifetest data=hodgkins outsurv=KM_data /noprint/; time maltime*mcens(0); strata age_gt30; run; proc sort data=KM_data; by age_gt30; run; data KM_data; set KM_data; by age_gt30; Failure = ...
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1answer
33 views

Pearson and deviance GOF test for logistic regression in SAS and R

I've been trying to fit exactly the same logistic regression model (same data) in SAS and R. As far as the coefficients are concerned I didn't notice any differences. However, when I tried to perform ...
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18 views

SAS HELP: Imputing both continuous and categorical variables in a single dataset

I am trying to impute data for missing observations within a longitudinal dataset following an arbitrary missing data pattern. Both continuous and categorical variables have missing data. I am ...
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28 views

Modeling Correlated Binary Data

I have data which looks like this: Subject ID (unique identifier), Group (Treatment or Control), Eye (Left / Right), Outcome (Success / Failure). The data is coming from a trial testing a new ...
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25 views

Using output from PROC LOGISTIC to derive predictions (with standard errors) for new predictor values

I can't figure out how to get predicted probabilities from PROC LOGISTIC. The output gives the predicted probabilities for each data point used to fit the model but I need to get predicted ...
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17 views

How to define unstructured covariance matrix in nlme? [duplicate]

My data involves repeated measures (26) of work completed by 7 participants during a protocol, under two conditions. I have constructed a model using lme4 as ...
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1answer
35 views

Interpretation of covariance estimates glmm (proc glimmix)

I am using the glimmix procedure in SAS to model a generalize linear mixed model with and binomial distribution and a logit link function. I am modeling both the G-side and the R-side covariance ...
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7 views

Suggestion requested for Modeling using SAS

I am expert SAS programmer and now I am interested in learning modeling using SAS. Please suggest me few books that I can use as start. Please also suggest few books/blogs/online tutorials that can ...
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25 views

Identify subgroup similar to another group [closed]

I have 2 groups of people (group2 is much larger than group1). The two groups have these attributes: demographic information and ...
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1answer
23 views

How to apply a model from one data set to another

I'm still new to SAS, and I need to take a basic OLS regression from one data set, and find the RMSE when applied to a different set. This feels simple, but I haven't found anything. Help would be ...
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34 views

How do i implement a zero inflated poisson inverse gaussian generalized linear model

Having spent a little time in solving these problem. it seems am getting nowhere yet. These are what i found out -the gamlss results is quite different from the zeroinfl function in pscl of R ...
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1answer
63 views

How to specify when a level shift begins and ends or in the case of data series with multiple level shifts how to id when one level shift beings/ends?

I am working on forecasting airport delays the data looks like this It looks like there is a structural break around 2004 where theres a huge increase and then a huge decrease around 2009. I am ...
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19 views

Pre-whitening of dynamic regressors

I'm not sure if this is the right approach for asking this question. I was going through this paper and couldn't completely understand the process followed. I have the below questions. After ...
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30 views

How to adjust ARIMA model for structural breaks?

I am trying to make an ARIMA forecast using the PROC ARIMA step, however there seems to be structural breaks in the data and when this is present it invalidates ARIMA results. I figure I can dummy out ...
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1answer
29 views

MSE in GLM ANOVA

Sorry for the wall of text, but I'm trying to figure out how to proceed and feel as though I need to clue you in as best I can. Experimental Design: Whole plot: Tree species (Spp) Subplot: Location ...
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64 views

use of proc autoreg to estimate parameters for ARIMA-GARCH model in sas

I have fitted my data to a seasonal ARIMA model. Now I want to analyze the variance of the time series data. I learned from sas tutorial to use proc autoreg, and model statement. However, the model in ...
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13 views

CV from a random effect model

I have some lab results. I have a continuous variable Y, and several factor variables X1, X2, X3 and X4. I want to perform a variance components analysis, and I have used SAS for doing so, my code is: ...
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1answer
78 views

what does “hessian is singular mean” in SAS proc nlin

Im trying to fit a power addictive nonlinear model, and keep getting a message in the results that convergence criterion met but hessian is singular. What does this mean? also in the correlation ...
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25 views

Variance Components Analysis

I have lab data, which is part of an R&R analysis. The data includes one numerical variable (let's call it Y), and a few factors (like site, day of running, lot,...), I will call them X1 X2 X3 and ...
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36 views

Dynamic regression and prewhitening

I'm working on a time series forecasting problem where sales needs to be predicted using weather variables. The weather variables are auto correlated and hence pre-whitening is needed to find the true ...
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1answer
75 views

Check for White Noise Residuals for AR(1) Model

I was going through the SAS documentation for PROC ARIMA and got stuck at this point. ...
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14 views

Using Proc distance with a very sparse matrix

I have a large sparse data set and I would like to apply segmentation of my customers. To give you an idea, I have more than 100 variables and 2.2 mln rows. Breakdown of my variables are as follows: ...
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1answer
28 views

Defining the likelihood function in survival analysis using SAS

I use proc lifereg procedure in SAS for survival analysis. In order to understand the process behind this procedure, I am trying to code the likelihood function and ...
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28 views

How to analyze split plot designs using SAS

I'm trying to improve my knowledge of SAS, as well as statistics, and understanding this example would help me to do both. In an agricultural study, a rectangular field is divided into two ...
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1answer
53 views

What methodology does proc varclus use to reduce the number of variables

In statistics, we can use methods like principal component analysis, linear discriminant analysis for variable reduction. In SAS, there is a proc called VARCLUS which is used for variable reduction. ...
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1answer
31 views

Dual Quasi-Newton Optimization on Zero Heavy Data (in SAS)

I am using PROC FMM in SAS, in attempt to use hurdle models on a data set with many zeros. There is one response variable and it's continuous, there are ~90 predictors (continuous - but contain many ...
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42 views

How does SAS calculate standard errors of coefficients in logistic regression?

I am doing a logistic regression of a binary dependent variable on a four-value multinomial (categorical) independent variable. Somebody suggested to me that it was better to put the independent ...
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31 views

Which statistical model/method should I use?

I have a data collected in New Jersey, and the units are individuals nested in four cities. Within four cities, there are also three types of neighborhoods defined by someone. I am trying to see if ...
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1answer
75 views

Using conditional logistic regression for repeated measures, complete separation (and secondarily, proc logistic)

I'm measuring a single binary outcome, with independent variables: 1) Treatment versus control. Each participant is one or the other. 2) "Before" versus "after" -- each participant has their outcome ...
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18 views

Compressing data for GLM

I'm doing survival analysis on a large dataset with various risk factors (e.g. blood pressure, age etc). I've prepared by converting from a per-life basis to the total exposure and deaths in each ...
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1answer
25 views

How to read data with two columns for y (dependent)? [closed]

I'm trying to fit a nonlinear model for the first time, so this might be a very dumb question. I have a simple data set: 1 column of x variable but for the dependent variable there are two numbers in ...
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12 views

The right covariance structure when correlations decrease with time, then increase and decrease again

I have been working on a longitudinal data set with 6 time periods spanning over 800 days overall. The time periods are not equally spaced and also they have an unequal width. For e.g. the first time ...
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36 views

How does SAS's stepwise logistic work?

Not being accustomed to reading documentation as a sequence of tables, I'd like to know if someone could kindly explain how SAS's Proc Logistic invocation with selection=backwards works. ...
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1answer
80 views

Factor extraction methods: Harris and Image extraction

Is Harris's (1962) extraction method considered a form of principal component analysis (PCA) or factor analysis (FA)? What about image extraction? I am using SAS and the documentation says: ...
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How to retrieve the group of variables most implied in duplicates?

How to retrieve the group of variables most implied in duplicates ? I believe a good start would be to retrieve the ordered list of the most together repeated groups of variables: Given a sample or ...