How do I analyse paired comparisons with an internal controlHello,
I am relatively new to JMP (currently using JMP 15) and I am struggling to identify how to analyse paired comparisons where each test subject has a control measure and an intervention measure at every timepoint.
The analysis being performed is looking at the change in continuous variable measured on the face over a defined time period, we know from experience that this variable fluctuates over time regardless of intervention therefore the face is split by left and right and the intervention is applied to one side of the face and the other side kept untreated as an internal control. Therefore each subject has 2 measures at each timepoint "intervention" and "control" and then is measured at baseline and T1 after a predefined length of treatment.
I have included a dummy set of data as an attachment that shows how the raw data is presented.
I want to perform analysis that will tell us if there is a significant difference between control and baseline measures within treatments and then a significant difference in change over time between treatments.
When I use the matched pairs analysis method I get the comparison for each treatment back to baseline but I cannot see a way to also get the intevention vs control analysis as the data we are working on is confidential.
Should I be using the fit model analysis for this comparison instead, if so how should I set up my model to get a paired comparison rather than an unpaired analysis?
@Emmanuel_Romeu
AnalyticsData TableRe: How do I analyse paired comparisons with an internal controlFirst of all, this is the JMP Community, so please provide examples in a JMP data table.
Please see this technical note about such analyses. Of course, come back with more questions if it does not suffice.
Re: How do I analyse paired comparisons with an internal controlHello Malcolm,
for repeated measure, Mixed Model (JMP Pro) is the appropriate analysis. I've attached 2 analysis, Residual and Unstructured which test various covariance structure, the lower AICc should help decide on which is the most appropriate (as Dummy variable here I did not conclude). Emmanuel
Re: How do I analyse paired comparisons with an internal controlHello Mark,
Sorry I am working from home today and therefore do not have access to JMP which is why my dummy data is in excel format, I will update the data table as JMP format when I have access to the software again.
Can you just confirm that my understanding of the technical note is correct that for my example I should attempt to use a multivariate approach where the T0 and T1 measures are in separate columns but aligned by row for each subject and treatment type and repeated measures is selected? Therefore my understanding is there is no way to perform the analysis I want when all the Time points are in the same column and assigned to a specific time point by a variable in another column, is that correct?
Re: How do I analyse paired comparisons with an internal controlHello Emmanuel, thank you for the additional information. It looks like I have some more evidence for my stakeholders as to why JMPpro would be a valuable purchase as most of our test data comes in this sort of format.
Re: How do I analyse paired comparisons with an internal controlMatched pairs tests are generally based on the difference, not the individual responses. Select the control measure data column and the intervention measure data column, right click at the top of one of them, and select New Formula Column > Combine > Difference or Reverse Difference, depending on the order of these two columns in your data table. You want to subtract the control measure from intervention measure. Now use the difference data column in the Y role.
Does that approach make sense? Is it appropriate for your purposes?
