Not to quibble, but it’s three-month rolling average, not a ninety day one. In polling parlance there is a difference. Ras polls party identification monthly and averages the past four months of data to get his targets. At the end of every month, the number from three months ago drops out of the average and is replaced with the number for the previous month. So the current targets are an average of three data points, party identification for June, July and August. Beginning Oct.1, the number for June will drop out and the number for Sept. will be added in.
If a 90 day rolling average was used, party identification would have to be polled every day and the number from 90 days ago would drop off each day.
The significance is that a three month rolling average, in an environment like the current one where Pubbie identification is increasing rapidly, understates McCain’s support more than a 90-day rolling average would.
I’m glad you quibbled, LNV. I prefer to be accurate.
Excellent post. Thanks.
“Ras polls party identification monthly and averages the past four months of data to get his targets.”
To be more precise, he averages data from three, two and one month ago. The current month is excluded for obvious reasons.