[Indy_Dh]

It looks like the confidence interval is larger in earlier years because there are fewer data points.

Whats interesting to me is how big the spread is until the 1900s where not only is the blossom date trend increasing, but the individual blossom dates are grouping much closer together as well. I wonder if this is an error in measurement or if there is natural explanation for this variance reduction in the last 100 years.

[SubiculumCode]

Ignore the error bars for a bit and look at the actual data points. The distribution is much broader than it is for the last 50 or so years.