All Questions
Tagged with sas repeated-measures
42
questions
3
votes
1
answer
126
views
Logistic regression with complete separation AND repeated measures
Consider a typical logistic regression on data with a binary response $Y$, and some predictor variables $X$'s.
I understand that when the event is rare, or in the case of complete separation, one ...
13
votes
2
answers
490
views
Beyond AR(1) as a covariance structure for mixed models with repeated measures
I have been reading about alternatives to assuming an AR(1) covariance structure for mixed models with repeated measures (in time). In particular I have heard about Toeplitz and Ante-dependence ...
- 304
0
votes
1
answer
37
views
GEE results showing opposite of true marginal relationship with EXCH working correlation
I am working on a modelling issue with two main effect variables: time period and Setting, related to an outcome, with all 3 being binary. My PI wants to test for moderating effects, so we have an ...
- 21
5
votes
1
answer
229
views
SAS Proc Mixed Repeated VS Random (or Both)?
I have data from a study for a "device". Subjects receive an implant and are followed for 5 years, with a checkup every year. A "disability score" is calculated from a survey every ...
- 51
0
votes
1
answer
1k
views
Mixed model for repeated measures with different timepoints and intervals
is there a way to design a mixed model for uneven number of measurements per subject and (more importantly) with uneven time intervals between measurements which are taken at different time points (...
- 23
2
votes
0
answers
56
views
Linear mixed model with repeated measures at two timescales
I want to use a Linear Mixed Model on the following design: 20 subjects with one between-subjects factor (10 males, 10 females). Each subject is measured at 4 timepoints: At 0 weeks, 2 weeks, 4 ...
1
vote
1
answer
39
views
Comparison between two groups of time series?
I have two groups of people. One group of people are healthy and the other group of people is sick. For people in both groups, I let them do exercise for 10 mins and then let them rest for 3 mins. I ...
- 123
4
votes
1
answer
667
views
Why would SAS proc mixed produce residual variance estimates under AR1 covariance structure, but none for unstructured covariance?
I am working on a program in SAS that seeks to extract r2 based on the residual variance produced by covariance parameter estimates in PROC MIXED.
The specification ...
- 41
1
vote
0
answers
35
views
Repeated Measures in Mixed Model - Creating Graphics [closed]
In learning about mixed modeling and how to perform this in SAS I came across this article
https://stats.idre.ucla.edu/sas/seminars/sas-repeatedmeasures/
However, I am not able to wrap my head ...
- 367
1
vote
0
answers
8
views
Data points (over time) that are both spatially even and odd
I have a set of data that has both spatially even timepoints (0, 7, 14, 21, 28 days) and spatially uneven (76, 99, 103, 133 days) timepoints. These are bodyweights collected at each of these days, and ...
0
votes
1
answer
336
views
SAS proc mixed Degree of freedom
I have a dataset in this format:
Factor A is a between subject factor (with 2 levels - High and Low).
Factor B is a within subject factor (with 3 levels - High , Moderate and Low).
I want to run a ...
- 207
3
votes
1
answer
99
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 ...
- 559
0
votes
1
answer
48
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 ...
- 113
1
vote
0
answers
108
views
ANOVA with Some Repeated Trials - Independence Assumption
I have some cross sectional data in which I would like to perform a basic ANOVA on. Some of the measurements are repeats from the same subjects, but the "independent variable" is not necessarily the ...
- 209
1
vote
1
answer
3k
views
Poisson regression with robust error variance - cross sectional study
To estimate RRs in a statistical model with a binary outcome, sometimes the modified Poisson regression can be used (proposed by Zou). Specially in epidemiology, when the incidence rate of the binary ...
- 679