Struggling to create a specific column
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!