Multilevel model with repeating repea... PreviousNext
Mplus Discussion > Multilevel Data/Complex Sample >
Message/Author
 Daniel Forster posted on Thursday, March 06, 2014 - 3:28 am
I am not sure if this belongs in Growth Modeling or here, but since my question has more to do with understanding multiple levels, I believe my question should go here.

Here is my situation, simplified:

Subjects were exposed to an intervention (or none) on the first day of the week for 4 weeks (i.e., treatment was received 4 times). Each week is essentially treated as a new beginning, so time starts at 0 on Monday (going by increments of 1 and ending at 6 on Sunday). Weeks are also measured as time points, beginning at 0 and ending at 3. Furthermore, all subjects complete the same tasks (with continuous and categorical outcomes) every day for the entire 4 weeks.

That said, I have days nested within weeks and weeks nested within people (who are modified by treatment). This is, at least conceptually, a 3-level model.

I want to examine changes within weeks and between weeks.

I have been looking to example 9.21 within the Mplus 7 User Guide (THREE-LEVEL PATH ANALYSIS WITH A CONTINUOUS AND A CATEGORICAL DEPENDENT VARIABLE). I am not sure how I should go about defining my clusters and within variables. When I try to cluster Days within Weeks (under the between command), I get an error since Days vary within the cluster.

Should I instead be thinking of this as a two level model, with Days and Weeks both as within-subject variables?
 Linda K. Muthen posted on Thursday, March 06, 2014 - 8:06 pm
Are the same subjects exposed to an intervention on the first day of each week? Can you show briefly how your data set looks?
 Daniel Forster posted on Thursday, March 06, 2014 - 8:39 pm
Yes, the same subjects are always either in the intervention or no intervention group. Again, just to be clear, the intervention is repeated on the first day of each week.

Currently my data is in long form, so it looks something like the data set below.

S is the subject number, C is a Between subject variable (i.e., intervention), W and D are Week and Day, respectively, V is the assessment version given on that day (Between Day, within subject variable), Rt is the continuous outcome and Ac is a categorical outcome.

S---C---W---D---V---Rt---Ac
1---1---0---0---1---200---1
1---1---0 1 1 250 1
1---1---0 2 0 100 0
1---1---0 3 1 430 1
1---1---0 4 0 200 0
1---1---1 0 0 200 0
1---1---1 1 1 300 1
1---1---1 2 0 220 1
1---1---1 3 1 510 1
 Daniel Forster posted on Thursday, March 06, 2014 - 8:43 pm
I am SO sorry about that. I accidentally clicked the "Post" button while editing. I was trying to make the data most spaced out. This probably looks a little better:

S___C___W___D___V___Rt___Ac
1---1----0----0----1---200---1
1---1----0----1----1---250---1
1---1----0----2----0---100---0
1---1----0----3----1---430---1
1---1----0----4----0---200---0
1---1----1----0----0---200---0
1---1----1----1----1---300---1
1---1----1----2----0---220---1
1---1----1----3----1---510---1
 Bengt O. Muthen posted on Friday, March 07, 2014 - 11:05 pm
Hard to say without digging deeper. You could perhaps do it as super-wide with number of dependent variables being days x weeks x 2 (Rt and Ac), so variation is across subjects.. Or less wide with number of dependent variables on Within being days x 2 (so Within is variation across time), and Between is variation across subjects.

You may also want to ask on Multilevelnet.
 Daniel Forster posted on Friday, March 07, 2014 - 11:28 pm
I was afraid you'd suggest doing wide formatting, since my actual data, using the terms of my days/weeks analogy, has 12 "weeks" (referred to as "sets" in my data) each with 160 "days" (referred to as "trials") for each week. That makes the task of doing super wide out of the question and less wide still a bit cumbersome. I'll see what I can get out of Multilevelnet.

Do you think it would be legitimate to do this as a two level model with weeks, days, and version all as Within subject variables, and treatment condition as my between subjects variable?
 Daniel Forster posted on Monday, March 10, 2014 - 4:29 pm
I am sorry if this is a ridiculous question, but where is Multilevelnet? Every search I do only leads to this discussion board.
 Bengt O. Muthen posted on Monday, March 10, 2014 - 4:45 pm
MULTILEVEL@JISCMAIL.AC.UK

One key question is if you want to model growth over the days of the weeks as a function of the early-weekday intervention, or if the days of the week are interchangeable.
 Daniel Forster posted on Tuesday, March 11, 2014 - 1:26 pm
Thank you for the info on multilevelnet.

To answer your question, we are interested in growth over the weeks as a function of the intervention, so days are not interchangeable. Also, we are interested in looking at the effect of the intervention on growth across weeks.

I believe what is happening is that we have two levels of time (days within weeks), both as within-subject variables.
 Daniel Forster posted on Tuesday, March 11, 2014 - 6:25 pm
I apologize, I believe I made a typo. What I meant to say was that we are interested in growth over the days of the weeks as a function of intervention, so days are not interchangeable. Everything else I said should be correct.
Back to top
Add Your Message Here
Post:
Username: Posting Information:
This is a private posting area. Only registered users and moderators may post messages here.
Password:
Options: Enable HTML code in message
Automatically activate URLs in message
Action: