The Meyer/Williamson matrix is a framework enumerating pretty much all potential causes of accidents in outdoor activities. I first ran across it in Deb Ajango’s Lessons Learned II, but I’ve had a really hard time finding an original source to cite. It appears to be taken from various presentations that Dan Meyer and Jed Williamson have given over several decades. There are various PDF versions floating around the web, but they tend to linkrot and I’ve never found a good HTML version. I’m reproducing it here so that I’ve got a good stable HTML version to link to in the future.