The previous two posts indicated that CNN, TWC and Intellicast had the best on-line weather forecasting accuracy by looking at the median and mean error in predicting daily low and high temperatures over 41 days. Is it possible to differentiate between those three?
For that, we need more data so I switched from summary statistics back to the data. In this new chart, the day by day errors were plotted. The gridlines labelled errors within 5 degrees, which is an arbitrary guideline for acceptable / unacceptable. The three scatters looked remarkably similar although CNN appeared to hit the bull's eye (the middle square) with less bias (errors more evenly distributed) but not much better accuracy overall (similar number of unacceptable errors).