Sure, but the rate is what helps to figure out why the change. If the rate of pedestrian death per mile walked is actually going down, but they are walking lot

Sure, but the rate is what helps to figure out why the change. If the rate of pedestrian death per mile walked is actually going down, but they are walking lots more, then you want to keep doing whatever you're doing, to keep the rate going down. If the rate per mile walked is going up, you need to consider some sort of about face, changing what you have been doing before.