I am working with a set of historical data that I did not collect myself. I cannot add to this data set in any way. For a 350-year period I have many thousands of data points, each associated with one of ~50 time points. Some of the time points have hundreds of data points associated with them, so I'm sure that those time points can be used in the linear regression. However, others have very few, even just one.
So my question is, how can I determine a cut-off for the time points that have enough data (and should be included in my regression) and the time points that do not have enough data (and should be excluded)? I'd like to do this in R.
Also, perhaps this is relevant - I'm interested in the minimum for each time point, not the mean. Thank you!