I don't know the Freakonomics methodology, but I'm pretty sure the analysis you're making isn't useful. We're talking about choices an individual homeowner can

I don't know the Freakonomics methodology, but I'm pretty sure the analysis you're making isn't useful. We're talking about choices an individual homeowner can make. Those choices are "install a pool" or "keep a gun in the house". To understand the risks for those two choices, total drownings and total gun deaths of children in the country aren't relevant to an individual's choice. To get a useful statistic, you need to know how many children died in their home pool in the sample group of homeowners w/ pools, and how many children died from a gun in the home in the sample group of homeowners w/ guns in the house. Because that's the choice -- do I put myself in this sample group or not? Think about powered trampolines -- suppose there are only five installed in the country, and on two of them a child has died this past year. That's a HORRIBLE risk, but with your method of assessment, it doesn't even show up. If you're thinking of installing this kind of trampoline, I'd highly recommend my method of analysis over yours.