Repeated measures ANOVA with missing data
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Hey all,
Brief info about my dataset: Cell counts from histological samples of liver tissue were taken for case and control patients. Each patient was supposed to get 3 readings done by a pathologist who counted the cells (but some patients only had 2 readings done). Need to find out if patients on the treatment had a higher/lower cell count than control patients. I was deciding between running a repeated measures ANOVA. However, I hit a snag with the latter model. Since I have missing data (2 instead of 3 slides read) for half my patients, the model delets those cases from the analysis. Is there a way to take the missing data into consideration in the repeated measures ANOVA? Syntax is fine but I'm not well versed in Python. Should I use some other model (mixed model, perhaps)? Or would it be fine to run a t-test using the average counts of each patient (would avoid the whole 2 readings vs 3 reading issue)? Thanks in advance. -Steve ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD |
Re: Repeated measures ANOVA with missing data
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You need to use a mixed model instead. This will make use of what data
is there (using maximum likelihood) and is much better with missing data than GLM, which uses listwise deletion in repeated measures. Paul R. Swank, Ph.D. Professor and Director of Research Children's Learning Institute University of Texas Health Science Center - Houston -----Original Message----- From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of Steve Sent: Thursday, June 19, 2008 6:35 PM To: [hidden email] Subject: Repeated measures ANOVA with missing data Hey all, Brief info about my dataset: Cell counts from histological samples of liver tissue were taken for case and control patients. Each patient was supposed to get 3 readings done by a pathologist who counted the cells (but some patients only had 2 readings done). Need to find out if patients on the treatment had a higher/lower cell count than control patients. I was deciding between running a repeated measures ANOVA. However, I hit a snag with the latter model. Since I have missing data (2 instead of 3 slides read) for half my patients, the model delets those cases from the analysis. Is there a way to take the missing data into consideration in the repeated measures ANOVA? Syntax is fine but I'm not well versed in Python. Should I use some other model (mixed model, perhaps)? Or would it be fine to run a t-test using the average counts of each patient (would avoid the whole 2 readings vs 3 reading issue)? Thanks in advance. -Steve ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD |
Re: Repeated measures ANOVA with missing data
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Also note that in order to use MIXED, you'll need to restructure your dataset. If you look at Help > Case Studies..., then Advanced > Linear Mixed Models > Using Linear Mixed Models to Analyze Repeated Measurements, there are instructions on how to restructure a file from variables to cases (i.e., originally set up for use in GLM Repeated Measures).
Cheers, Alex -----Original Message----- From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of Swank, Paul R Sent: Friday, June 20, 2008 10:29 AM To: [hidden email] Subject: Re: Repeated measures ANOVA with missing data You need to use a mixed model instead. This will make use of what data is there (using maximum likelihood) and is much better with missing data than GLM, which uses listwise deletion in repeated measures. Paul R. Swank, Ph.D. Professor and Director of Research Children's Learning Institute University of Texas Health Science Center - Houston -----Original Message----- From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of Steve Sent: Thursday, June 19, 2008 6:35 PM To: [hidden email] Subject: Repeated measures ANOVA with missing data Hey all, Brief info about my dataset: Cell counts from histological samples of liver tissue were taken for case and control patients. Each patient was supposed to get 3 readings done by a pathologist who counted the cells (but some patients only had 2 readings done). Need to find out if patients on the treatment had a higher/lower cell count than control patients. I was deciding between running a repeated measures ANOVA. However, I hit a snag with the latter model. Since I have missing data (2 instead of 3 slides read) for half my patients, the model delets those cases from the analysis. Is there a way to take the missing data into consideration in the repeated measures ANOVA? Syntax is fine but I'm not well versed in Python. Should I use some other model (mixed model, perhaps)? Or would it be fine to run a t-test using the average counts of each patient (would avoid the whole 2 readings vs 3 reading issue)? Thanks in advance. -Steve ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD |
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In reply to this post by Steve-41
Thanks Paul, Alex and Sara,
I was afraid that I might have to use mixed models. Also, thanks to both Alex and Sara (whose emails didn't go to the list and I'm posting below) for giving me the heads up on restructuring the dataset. It was originally structured for a linear analysis and I had restructured it for the ANOVA... so it's back to drawing board. Thanks again for the tips. -Steve ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sara House wrote on Fri, Jun 20, 2008 at 9:13AM Steve - If you use a mixed model, you wouldn't lose all your cases with missing values. Instead, you would be able to use all cases that have data at a particular time. At the risk of sounding like Don Hedeker's personal cheerleader (I've recommended his site on this list before), if you go to http://tigger.uic.edu/~hedeker/ you'll find SPSS and SAS syntax to do mixed-model analyses with continuous data, and SAS syntax for dichotomous data. BTW, does anyone know if there is a way to do mixed model analyses with dichotomous data in SPSS? I don't have access to SAS at work and I'm more familiar with SPSS anyway. Sara ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sara House wrote on Fri, Jun 20, 2008 at 11:43 AM Steve - Oop, sorry, didn't realize my first email went only to you and not the list. You can ignore the question in my email. Also, Alex is right that you'll want to restructure your file. So instead of: ID T1Meas T2Meas T3Meas 1 x y z 2 ... You'll want a single measurement variable and then a time variable: ID Meas Time 1 x 1 1 y 2 1 z 3 2 ... Hope this helps! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD |
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In reply to this post by Steve-41
Hi,
your explanation is clear but I am having the same problem and I would need more details if possible. I have understood that I will restructure my data with time points in each row. But..the groups? I also have two groups (case and control) and how will the groups be organized? And then, how do I have to proceed to do the analysis? Thank you Francesca 
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Re: Repeated measures ANOVA with missing data
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Francesca, where does this come from? According to nabble, you are replying to the last post of a message originally posted in 2008. You're having problems, I understand that but what is/are the problems that you are having? Please describe them, what you've tried to do and how what you tried failed. It sounds like this is a pretty ordinary varstocases problem.
Gene Maguin -----Original Message----- From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of francesca Sent: Saturday, February 21, 2015 4:44 PM To: [hidden email] Subject: Re: Repeated measures ANOVA with missing data Hi, your explanation is clear but I am having the same problem and I would need more details if possible. I have understood that I will restructure my data with time points in each row. But..the groups? I also have two groups (case and control) and how will the groups be organized? And then, how do I have to proceed to do the analysis? Thank you Francesca -- View this message in context: http://spssx-discussion.1045642.n5.nabble.com/Repeated-measures-ANOVA-with-missing-data-tp1082833p5728764.html Sent from the SPSSX Discussion mailing list archive at Nabble.com. ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD |
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Hi, thank you very much for this. I think I made a mistake as I posted my trouble in someone else's post. I have problems because I need to perform a two way repeated measures ANOVA with SPSS but using the mixed model, since some data are missing and I therefore can't perform the classic one. I have understood that I need to rearrange my data and have them ordered with the repeated measure in vertical. But I also have a "between" factor (I have two groups). If I put the time in vertical for each subject, how will I organize my groups? And once the table is ready, how do I perform the two way repeated measure using the mixed model? On internet I have only found instruction for the one way but it does not apply to my case. I hope my explanation is clear enough? It would be very nice if you couls have any suggestion on that Thank you very much Francesca 2015-02-23 15:32 GMT+00:00 Maguin, Eugene [via SPSSX Discussion] <[hidden email]>: Francesca, where does this come from? According to nabble, you are replying to the last post of a message originally posted in 2008. You're having problems, I understand that but what is/are the problems that you are having? Please describe them, what you've tried to do and how what you tried failed. It sounds like this is a pretty ordinary varstocases problem. |
Re: Repeated measures ANOVA with missing data
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Dear Franceska, Check this paper: Van Ginkel, J.R. & Kroonenberg, P.M. (2014).
Analysis of variance of multiply imputed data.
Multivariate Behavioral Research, 49, 78-91. This paper provides you the tools to carry out a repeated measures ANOVA in SPSS on multiply imputed data sets. It’s better than using the multilevel approach
for handling the missing data because multiple imputation can also take into account dependence of the missing data on variables that are not included in your analysis. Best, Joost
From: SPSSX(r) Discussion [mailto:[hidden email]]
On Behalf Of francesca Hi, thank you very much for this. I think I made a mistake as I posted my trouble in someone else's post.
I have problems because I need to perform a two way repeated measures ANOVA with SPSS but using the mixed model, since some data are missing and I therefore can't perform the classic one. I have understood that I need to rearrange my data and have them ordered with the repeated measure in vertical. But I also have a "between" factor (I have two groups). If I put the time in vertical for each subject, how will I organize
my groups? And once the table is ready, how do I perform the two way repeated measure using the mixed model? On internet I have only found instruction for the one way but it does not apply to my case. I hope my explanation is clear enough? It would be very nice if you couls have any suggestion on that Thank you very much Francesca 2015-02-23 15:32 GMT+00:00 Maguin, Eugene [via SPSSX Discussion] <[hidden email]>: Francesca, where does this come from? According to nabble, you are replying to the last post of a message originally posted in 2008. You're having problems, I understand that but what is/are the problems that
you are having? Please describe them, what you've tried to do and how what you tried failed. It sounds like this is a pretty ordinary varstocases problem.
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Re: Repeated measures ANOVA with missing data
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In reply to this post by francesca
Ok. So your data must look like this for a one between (group=A or B)-one within (time=1 or 2) ANOVA. Gene Maguin Id group time1 time2 11 A 3 7 12 B . 5 13 A 2 . 14 B 4 3 And so on. Varstocases make DV from time1 to time2/index=time. The result should be: Id group time DV 11 A 1 3 11 A 2 7 12 B 2 5 13 A 1 2 14 B 1 4 14 B 2 3 From: SPSSX(r) Discussion [mailto:[hidden email]]
On Behalf Of francesca Hi, thank you very much for this. I think I made a mistake as I posted my trouble in someone else's post.
I have problems because I need to perform a two way repeated measures ANOVA with SPSS but using the mixed model, since some data are missing and I therefore can't perform the classic one. I have understood that I need to rearrange my data and have them ordered with the repeated measure in vertical. But I also have a "between" factor (I have two groups). If I put the time in vertical for each subject, how will I organize
my groups? And once the table is ready, how do I perform the two way repeated measure using the mixed model? On internet I have only found instruction for the one way but it does not apply to my case. I hope my explanation is clear enough? It would be very nice if you couls have any suggestion on that Thank you very much Francesca 2015-02-23 15:32 GMT+00:00 Maguin, Eugene [via SPSSX Discussion] <[hidden email]>:
View this message in context:
Re: Repeated measures ANOVA with missing data |
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