Hmm, so in this example, there are maybe 123 good data points to calculate carry between GBM Dec and March, and I get similar numbers: -5% average carry over those 123 days. Between March and June I have fewer good data points for the same date range, about 65. Averaging carry over that range is 4%.
So still very different numbers even smoothed, and not really 180 data points to smooth across.
Or do you mean smooth the carry calculation after rolling multiple contracts over that 180 day period? (I've seen that being used in some cases to smooth commodity seasonality.) Thanks!