I am running a survey which I’m using to test the effect of varying incentive values on response rates. I have a maximum budget of Y which I must not exceed. I have incentive values of x1, x2, x3, x4, x5, and x6 which will be randomly distributed across my sample. I would like to have my survey “quota” be responsive to the sum,

S = C1x1 + C2x2 + C3x3 + C4x4 + C5x5 + C6x6

where Ck is the count of responses for the given incentive group, such that it will disallow any responses once S = Y. (So S must always be less than or equal to Y.)

I’ve contacted support and they said there is no way to do this with Qualtrics’ native quota functionality, but suggested asking here to see if anyone has an idea how to accomplish this with custom coding. 

If you have a solution, please be specific; I don’t have much experience with custom coding in Qualtrics apart from simple formatting.

Thanks in advance for any guidance!