Re: Options for Dealing with Missing Data in Mixed ANOVA

Posted by Bruce Weaver on Feb 21, 2017; 6:12pm
URL: http://spssx-discussion.165.s1.nabble.com/Options-for-Dealing-with-Missing-Data-in-Mixed-ANOVA-tp5733847p5733855.html

You say that using the MIXED procedure is beyond your ability at this time.  I think you are giving up far too easily on that approach.  It sounds like your analysis is structurally identical to one of the examples on this UCLA page:

  http://www.ats.ucla.edu/stat/spss/seminars/Repeated_Measures/

Scroll down to "Exercise example, model 2 using MIXED Command".  In that example, Exercise Type is a between-Ss factor and Time a repeated measures factor.  So you have a good model of what your MIXED syntax should look like.  

Re LOCF, you might find David Streiner's short note on it useful.

  http://ebmh.bmj.com/content/11/1/3.2

HTH.

Brooklyn wrote

Hi,

I am looking to assess the effect of an intervention (vs control) on a number of outcomes at 4-time points. I have one between-groups IV (group) and one within-groups IV (time) and many continuous outcomes (DV) and am therefore looking to do a Mixed ANOVA.

I know a linear mixed effects model is better at dealing with missing data, but I think this is beyond my ability at this point in time.  I have also read a lot that suggests carrying forward the last observation is never a good idea and can introduce more bias. I am going to check to make sure the missing data points are not correlated to demographic variables as well.

Is carrying forward the last observation (LOCF) for missing time points suitable in mixed ANOVA or is there another way I could be dealing with this - other than perhaps running the mixed ANOVA on both the original dataset and the LOCF dataset?

Thank you for your help
Brooklyn