Reihan: Understanding the Casualty Numbers

What should one take away from these apparently-encouraging casualty numbers? I mean this

The number of American troops and Iraqi civilians killed in the war fell in September to levels not seen in more than a year. The U.S. military said the lower count was at least partly a result of new strategies and 30,000 additional U.S. forces deployed this year.

and this

More dramatic, however, was the decline in Iraqi civilian, police and military deaths. The figure was 988 in September - 50 percent lower than the previous month and the lowest tally since June 2006, when 847 Iraqis died.

Pro-surge commentators seem confident that this is a byproduct of the surge, and that this is a sign of progress to come provided we stick with their proposed strategy. I imagine there's another interpretation. Who has the best take?