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.
719
questions
1
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0
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115
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Using percentiles instead of mean for the parameter of the response variable in regression
I want to do a linear regression in SAS between two variables. What I would get is the parameter for the mean of my response variable (and the 95% confidence interval for the parameter), but that is ...
0
votes
0
answers
99
views
Noninferiority in a multilevel model
I am working on a randomized trial in which patients were randomized to one of two groups and followed over time, they were assessed at 5 time points including baseline. The outcomes include ...
0
votes
1
answer
175
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tau2 estimation using reml in SAS
I would like to obtain tau2 estimation using REML by making use of PROC MIXED procedure in SAS to compare the estimation result obtained from rma function in R.
I have used the following SAS code;
...
1
vote
0
answers
77
views
Logistic regression and unbalanced sample [duplicate]
I am running a logistic regression in SAS where the outcome variable is a binary on sale success (IVs are: location of the customer, Vendor, handling time, experience level of sales person etc.). ...
4
votes
4
answers
1k
views
Why does lmer (unlike SAS) output a non-zero variance of random effect if it is also included as fixed: (1|site) + site?
(I am completely editing my post. The root question is the same, but I am now posting simulated data to illustrate my issue).
I ran (I beleive) the same model in both proc mixed and R (lmer) but have ...
0
votes
0
answers
280
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Is the supremum test of cumulative martingales residuals OK to assess proportional hazards of both groups and covariates?
Is the supremum test of cumulative martingales residuals (as implemented by assess in SAS PROC PHREG, and other software) OK for testing PH of both continuous ...
2
votes
1
answer
2k
views
Why does SAS Cochran-Mantel-Haenszel seems different than others?
I've been asked to compute a Cochran-Mantel-Haenszel (CMH) Test on 2 variables :
one is an ordered factor from quantiles of a numeric value ("Q1", "Q2", "Q3", "Q4")
the other is an unordered ...
2
votes
1
answer
602
views
Reproducing SAS Factor Analysis in R
I need to be able to reproduce some SAS results in R, as far as this is possible (note: I'm very familiar with R and barely used SAS). The original SAS code is as follows:
...
1
vote
1
answer
977
views
Confidence intervals for Hazard ratio - sas weibull AFT
I have a doubt with Weibull Accelerated failure time model Hazard ratio's confident intervals interpret from SAS output, thake this as an example:
...
1
vote
1
answer
851
views
Paired binary data with a zero cell
How do you analyse and obtain a p-value from a 2*2 table examining a binary outcome that is paired, when one cell has zero events?
To clarify, I was looking at the success rate of obtaining an ...
1
vote
0
answers
99
views
GEE analysis using proc genmod block effect
I have done an experiment with two factors in RCBD, bionomail distribution.
I wanna use GEE in Proc Genmod in SAS to analyze the data as follow:
proc genmod data=Emerg;
class obs Crop Dist Block;
...
1
vote
0
answers
112
views
How to write a combination Seasonal ARIMA model in mathematical form
I'm doing a forecast combination model in SAS: the first is an ARIMA (10, 0, 1)(0,1,1)s NOINT with a point intervention at t=3
And the second is a MA model with only lag 13 and simple differencing d =...
0
votes
1
answer
1k
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SAS Proc lifereg phreg and lifetest - survival plot
I have to draw a survival probability plot with three different surviuval estimates using the phreg, lifereg and the lifetest procedure with sas for make a confrontation
the models:
...
0
votes
1
answer
762
views
AFT Weibull model (SAS) hazard ratio
I'm trying to calculate the hazard ratio between two classes, from a variable composed by three classes, i'm modelling an AFT weibull model with this and other indipendent variables
for example my ...
0
votes
1
answer
1k
views
Using PROC QLIM OUTPUT to get predicted values from a two-step Tobit model
I am fitting a two-step Tobit model through PROC QLIM in SAS. The first step of the model is a probit model for whether someone "responds" (e.g. makes a donation). The second step of the model is ...
3
votes
0
answers
3k
views
Interpreting Phillips-Perron Unit Root Tests
I would like to make sure that I'm properly understanding how to interpret the Phillips-Perron Unit Root Tests available in SAS. The best resource that I've been able to find was this page: https://...
1
vote
0
answers
293
views
Survival analysis with multiple time-dependent covariates
I have data on patients receiving an SPK (simultaneous pancreas-kidney) transplant. Of interest is the effect of developing the BK virus post-tx on outcomes such as death-censored graft survival. I ...
1
vote
1
answer
875
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Survival analysis - time-dependent covariate with left truncation
I have some data on patients receiving pancreas transplants. Some of these patients have a procedure done post-transplant called enteric conversion, and I am looking at the effect of this conversion ...
0
votes
1
answer
767
views
Repeating AIC values with proc Glimmix in SAS
I am comparing several models using PROC GLIMMIX, and many of my models are coming out with the exact same AIC value, even when new variables are added. For example, the code below yields the exact ...
2
votes
0
answers
39
views
Cox-Hazard Ratio differences in Software suits; Manual calculation
Working in clinical research my task is to calculate the Hazard ratio, better to check the calculations of someone else. This first calculation was based on ARM=(3 different treatments) with only t=(...
2
votes
1
answer
1k
views
No intercept model with more than one factor
I am using SAS for linear regression with two independent categorical variables. When I run models with each categorical variable separately, I get estimates for every level of both variables. This ...
1
vote
1
answer
242
views
interpretation and inclusion of interaction terms in regression model
I have a 3-way interaction model as follows:
Y = A + B + C + A*B + A*C + B*C + A*B*C
A is a dummy and B and C are centred continuous variables.
I am mainly ...
0
votes
1
answer
924
views
Interpret odds ratios of ordinal independent variable in logistic regression
I have a set of data where I would like to do logistic regression modeling the odds of a binary outcome variable (Therapy), with Stage as an ordinal explanatory variable (0,1,2,3,4). I am using SAS. ...
1
vote
1
answer
410
views
Building a Generalized Linear Mixed Model in SAS
I am building a generalized linear mixed model in SAS. Unfortunately, this is the first time I’m working with GLMMs and I am not very familiar with SAS. I have been using proc GLIMMIX. I have data ...
1
vote
1
answer
1k
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Cox Proportional Hazards Model with Time-Dependent Covariate and Late Entries in SAS [closed]
I am trying to fit a model in SAS that allows for both late entries (i.e. left truncation) and a time*covariate interaction. I can fit both separately:
Late entries:
...
1
vote
0
answers
38
views
SAS logistics regression prediction [closed]
I am making a model to discern people who would most possibly buy
stock then offer a list for the bank to make a better sales calling.
I have selected some features and create some features based on
...
1
vote
0
answers
87
views
Responding to reviewer concerns re: MANOVA
We conducted a study examining how individuals rate other individuals ("targets") on the basis of information about their exercise status. The IVs are rater exercise status (low, medium, high) and ...
0
votes
0
answers
29
views
applying standard regression techniques to time series prediction via second level forcasting
The author of the book:
Practical Time Series Forecasting with R: A Hands-On Guide
suggests fitting a second level forecasting model to the residuals of a standard (first level) regression model in ...
2
votes
1
answer
97
views
How to test for dose effect in non-linear model
I would like to examine whether there is an effect of dose in a data set that looks at repeated measurements over time. I expect the dependent variable to decrease exponentially over time. My ...
0
votes
0
answers
57
views
Multi Level Dependent Variable Statistical Test
I have a multi level dependent variable. The dependent variable is Tenure - less than 1 year, 1-2 year and above 2 years.
The independent variable is AHT. I need to conduct a statistical test ...
0
votes
3
answers
263
views
How to apply Two-Factor ANOVA in SAS when I only know the counts of each outcome?
I am confused about how to apply two-factor ANOVA when I get actually no real data, but only count for each outcome, because the dependent variable is categorical, and is binary (only 0 and 1), and I ...
1
vote
0
answers
39
views
including baseline value for outcome in multi level logistic regression
I am trying to predict poor vs. high self rated health in a multi-national survey with complex sampling. I have two time points and I am using proc glimmix in SAS with cluster and sample weights. All ...
1
vote
1
answer
103
views
How to Model a time series with another using Machine Learning
I have two time-series and I need to make a model that takes the input of one of the time series to estimate the value of the other time series. I've tried a lot of different specification of ARIMA ...
0
votes
2
answers
745
views
Value of t statistic equal to infinity
Does anyone know when PROC REG with selection = stepwise in SAS gives t-values equal to infinity?
I am getting an $R^2 = 1$. My data set has $n = 50$ observations ...
0
votes
0
answers
172
views
SAS PCA first 10 eigenvalues only explains 10% of the variance
I am running a Principal Component Analysis on intra-day second level returns of all the stocks that trade in the U.S.
The matrix is constructed as
where each row is the return of all stocks in ...
2
votes
0
answers
1k
views
Calculating Effect Size for Generalized Linear Models
I have measured spore production by a parasite after feeding the host on 4 diets of varying nutritional content. I have primarily analyzed the data by treating the diets as categorical variables, even ...
1
vote
0
answers
708
views
Multiple nest structure for lme()
I want to build a mixed-effects model with multiple nest structure in R. For example, month nested in year, day nested in year and year. Response variable Y is temperature and predictor variable X is ...
0
votes
0
answers
203
views
Strategies for model selection of non-nested GLMM models
What are the best strategies to select between a small collection of possible models when the models are non-nested and modeled using a GLMM with correlated residuals (longitudinal random effects or $...
1
vote
0
answers
80
views
Parametric survival curve in middle of observation window
I am fitting a parametric survival model with a Weibull distribution that has pretty good results when checking the 12 month predictions versus the actual results. The issue I'm seeing is when looking ...
1
vote
0
answers
154
views
How do I use the "correct" error term in PROC MIXED to conduct specific contrasts?
I have a SAS PROC MIXED question and I hope that y'all would be able to help me. It is my first time posting a question on here.
First, an analog to help define the question: Imagine that a ...
1
vote
1
answer
527
views
trough detection in time series
I have time series (daily readings), which can trend downwards. I would like to introduce a dichotomous dummy variable that indicates when the time series contains a trough (dummy=1) or not (dummy=0). ...
0
votes
1
answer
47
views
Does it make sense to specify a repeated effect that does not appear in the model?
The concentration of a certain nutrient is measured in soil each fall after harvest in a set of research plots. I want to model the change in nutrient concentration over a number of years, but I'm ...
1
vote
1
answer
1k
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How to use nearest neighbor to find similar population based on list of features
Nearest neighbor can classify new data point based on the k nearest neighbor's class. Assuming there is dataset A contains 10000 data points. There is also another dataset B contains 1 MM data points. ...
0
votes
0
answers
93
views
"Uniform" Clustering
I have the data $\{(y_i,\omega_i), i=1,\dots,n\}$, where $y_i \in \mathbb{R}_+$ the response and $\omega_i>0$ a weight.
Fixed $K>0$ I want to determinate $y_1^*,\dots,y_{K-1}^*$ such that
$$
\...
-2
votes
1
answer
138
views
Probability models in SAS [closed]
What sort of tests are available in SAS that allow you to figure out what the probability of an event occurring is? And I do mean probability, not odds.
Specifically, I would like to know what is the ...
1
vote
0
answers
103
views
Logistic Regression Interaction vs conditioning on one level
I have a data set where the outcome is binary, and is fit as a function of two categorical variables (3-level location and 2-level status) and their interaction. I am interested in two things:
...
0
votes
1
answer
426
views
Proc mixed in SAS with a random and repeated factor [closed]
I need to carry out a comparison test for the measures of absorbance between 2 types of tank: glass tank and plastic tank. The technician in the laboratory took randomly 5 plastic tanks and 5 glass ...
0
votes
1
answer
492
views
PROC FACTOR SAS vs. prcomp() R
I wanted to know if anyone has ever come across research that was done comparing the output of a Principal Component Analysis (PCA) for PROC FACTOR in SAS versus the PCA output using the prcomp() ...
1
vote
0
answers
133
views
PCA: Dimension Reduction
I ran PCA.
Output is:
.
I am trying to increase the R-Square Value. In doing so, I want to only consider important variable.
Till now I have cleaned the data by excluding the outliers and also by ...
0
votes
1
answer
227
views
Count data model but also dealing with multiple comparison ? [closed]
I'm working on a project dealing with different treatments on the number of medical service in 1 year.
I used negative binomial regression to estimate incident rate ratio after adjusting other ...