Tom mentioned that on average, the male-female strength advantage was 5 to 3, or 1.6667. That’s based on a very general description, an old, but detailed study suggested by a commenter here has it at 1.8942. The world powerlifting records tend to support the latter, as the male record is 1,008 pounds and the female is 551 pounds, or 1.8294.
But it’s not enough to merely end the equation with strength alone, as in a physical confrontation that greater male strength is applied to a smaller female size and vice-versa. Wikipedia gives the average American male weight in 2002 as 191 pounds, while the average weight for women is 164.3, an ratio of 1.1625.
Height is generally considered an advantage due to reach, but I don’t consider it enough of one to factor into the situation, especially since taller fighters often have trouble with shorter ones who easily get inside them. Speed, however, is absolutely crucial since it not only determines who is more likely to get strikes in, but also how hard those strikes land due to the old F=MA. Due to the specific training and drug use by both male and female professionals, I think the national junior records for the 100m dash are a better comparison, the male time of 10.06 seconds is almost a full second faster than the best female time of 11.04, a ratio of 1.0974.
The fourth factor that should be incorporated, but probably can’t be, is the ability to absorb force. However, mass is certainly a part of this, so we will assume for the time being that this is factored into the weight factor.
Putting these factors together gives a result of 2.3338. This might not sound like all that much more than Tom’s original 1.6667, but consider that it is the equivalent of matching up two 5’9″ men of equal speed who each weigh 191 pounds, one whom benches 135 pounds while the other benches 315.