If it can be established increased troop levels have been producing a positive effect on the security situation, that not only means that there is some hope for future stabilization through a troop increase, but that American forces have had and are having a net positive effect on Iraqi security levels now. If, on the other hand, no correlation between troop levels and violence levels can be established, the logical conclusion is American troops have been contributing very little to stabilizing the Iraqi situation, in any numbers. Regrettably for supporters of the Stuntz argument, given the statistical data to date, the latter seems the stronger conclusion.

This is worth a look, but I think he needs to look at the whole security picture and not just US fatalities.