I'm trying to run regression analysis on a dataset that features a pair of continuous variables that are collected at a certain time (in days). Whilst the data should be collected at a specific time, due to various restraints there can be a considerable difference between the intended collection time and the actual collection time, which has in turn means that I have less trust in the data (later means less efficacy).
What could be some good ways to account for this variability, as it's on an observation-by-observation basis?
Off the top of my head I was thinking of scaling the variable by an appropriate distribution that relates to the efficacy change, or just by the number of days itself, but I'm no statistician and could do with some ideas!
Thanks, Dan