I'm retired, no one's paying me to spend the time to gather the data properly and to look for patterns. Like you said, in another post. You're doing word problems, at an 8th grade level maybe (probably even lower, the kids are learning a lot more math at earlier grades these days.)
Your person hours idea isn't a terrible way of looking at it. But, you have to start at the beginning and decide if the initial question even makes sense. No one starts a hike with 100% certainty that they'll be a successful thru-hiker. There are questions on what makes a specific hiker more, or less vulnerable, there are questions on the motive of the murderers, there need to be control groups, the sample size of murders is tiny!, and that creates it's own problems with statistical significance.
My initial point is correct however, as there are already quite a few people tossing out variants of the 7 out of 100,000 number as of it's gospel. It isn't.
How to correct this number and this conclusion. I can't even explain everything wrong with it without hours of effort. At a minimum you'd have to take a solid college statistics course or two to even understand what's involved. Here's a link to just a basic structure of how to conduct a study.
http://gchang.people.ysu.edu/class/pstudy.htm
If I were world emperor, every High School would require a statistics course, a formal logic course and a debating course.
Edit: My posts sometimes come across as know it all, so I'll just state that there's a hell of a lot I don't have a clue about. Bad statistics just happens to be a peeve of mine.