About Melk

Melk · ‎08-01-2017

Would reviewers frown if results are reported without any formal statistical tests in such a case? I am wondering what is commonly done in such a scenario.

Melk · ‎08-01-2017

Anyone have input on this?

Melk · ‎08-01-2017

Thank you both! LET statement was a typo, both worked beautifully.

Melk · ‎08-01-2017

I want to create a date variable in my program from a macro %LET statement. %LET date9 01AUG2017; data new; set old; date = &date9; run; I cant get this to work, I dont quite understand how the date9 is stored in SAS I think - adding a format statement also doesnt work. What am I missing here?

Melk · ‎07-20-2017

THank you. I have been looking into this suggestion, would I interpret the "Trial" fixed effects to be able to conclude that my mean 'post' Y is significantly greater than my mean 'pre' Y?

Melk · ‎07-17-2017

So is time a SAS keyword here?

Melk · ‎07-17-2017

The time intervals for each trial/subject can vary - some have 5, some have 3, and the timepoints where measurements were taken were random (e.g. subject 1 had measurements at 5, 16, 21, and 27 secs while subject 2 had measurements at 3, 10, and 19 secs). Y has a close to linear relationship with time.

Melk · ‎07-17-2017

Yes, a big confusing! At each trial (pre and post) the subject performed a task repeatedly over an interval of time, measurements were recorded at random intervals of time (5 secs, 10 secs, 18 sec, etc.)

Melk · ‎07-16-2017

Data is longitudinal; trial = pre or post variable.

Melk · ‎07-14-2017

Actually, I am a little new to the glimmix procedure, so forgive me. When I run the model with the above code, trial is insignificant When I remove the interaction and just run the model on trial, trial becomes significant. Based on my reseach question - is it ok to remove the interaction ?

Melk · ‎07-14-2017

Thank you, I think I should be interpreting the time by trial interaction here, but the research question actually has nothing to do with difference by time- would it be more appropriate to report just the estimates for trial? When I run the model with the above code, trial is insignificant When I remove the interaction and just run the model on trial, trial becomes significant. Based on my reseach question - is it ok to remove the interaction ?

Melk · ‎07-14-2017

I am trying to run a mixed model on a very small number of subjects with pre-post data. the data was collected over time simply due to the nature of the intervention, the collected timpoints pre and post and between patients are totally random and not equally spaced. I want to simples conclude that the post was better than the pre (which means the post values are greater, overall, than the pre). After some research, I came up with this model: proc glimmix data=long; class Trial id; model y = Trial | time / solution; random intercept / subject=id; random intercept time/ subject=Trial*id type=sp(pow); run; quit; Can anyone confirm that this indeed the best way to model this research question? If so, I am getting the error message: ERROR 79-322: Expecting a (. ERROR 76-322: Syntax error, statement will be ignored. at the end of the second random statement. Cant see to figure out why. Any help would be appreciated.

Melk · ‎07-10-2017

Thanks so much!

Melk · ‎07-10-2017

Well, I thought that since the training data was used to fit the test data, which is a different portion of the main dataset each time, those predicted probabilities could be used to get an "average" ROC (by basically combining each of the test datasets, each with predicted probabilities of the outcome, together). So, I basically have a dataset with my outcome, predictors, and predicted probabilities from my k fold CV and dont know how to construct the ROC curve.

Melk · ‎07-10-2017

How to create the graph, but it would also be useful to calculate the AUC. I essentially have output predicted probabilities from fitting my training data on each of my test data, I just dont know how to use this to create the ROC curve, ultimately get the AUC.

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