Estimating confidence intervals, part 3

Another episode in our continuing series of effort estimation in the small with 90% confidence intervals. I recently finished implementing another feature after doing the effort estimates for each day. Here’s the plot:

 

Once again, I underestimated the effort even at the 90% level, although not as badly as last time. Here’s a plot of the error.

I also find it takes real mental energy to do these daily effort estimates.