Struggling to create a specific column
Hello everyone,
This is my first post here, so I apologize if I am formatting my question incorrectly.
I am busy preparing to conduct an experiment focused on the pupillary responses to various images (attached is a reference image of my preliminary data). To attain an actual measure of dilation, I need to subtract each subject's control response from their critical response (left and right eye values averaged = LR Average). It is crucial that this subtraction is within-subject, as pupil size varies at the individual level.
I have also attached a screenshot of the incomplete computation to better explain what I am trying to do. In essence, I would like the "mean(LR Average)" that is being subtracted from the initial "LR Average" to exclusively be the average pupil response to "controlimage2.png."
So it would look like: (LR Average - mean(Control LR Average)/SD(LR Average) | ParticipantName
Any and all advice would be greatly appreciated. Please let me know if I can provide more information!
Comments
Hi bertheat,
Unfortunately, I don't think it is possible to do this with the drag and drop interface right now.
A workaround is to use R code, like so:
dataVar <- contNormal # change this into LR Average groupVar <- facFive # change this into ParticipantName result <- 0 * dataVar gg <- unique(groupVar) for (g in gg) { idx <- groupVar == g result[idx] <- scale(dataVar[idx]) } resultyou can enter R code by selecting the R symbol when creating a computed column:
After you do that, you can check with Descriptives if it worked out:
The values for the mean are of order 1e-17, which is essentially zero.
Let me know if this works!
Cheers,
Don
Hey Don,
Thank you so much for replying so thoughtfully! I'll give that a go and let you know how it turns out.
Lambert