Hi Mike, Thanks for raising this issue and the challenges in adopting holdouts with time series data. Good discussion and worth calling attention to the need for multiple perspectives (and to try new things) on deriving additional insights from time series data. In customer conversations over the years, it would appear there is considerable untapped value in time series data. The time dimension of data has a lot to offer in forecasting, time series mining.... Btw, looking forward to seeing your book in print next month!