I don’t follow it but your last suggestion (use single income not household) was new to me and interesting in as much as it seems like an obvious extension of “

I don’t follow it but your last suggestion (use single income not household) was new to me and interesting in as much as it seems like an obvious extension of “The Two-Income Trap” thinking. To some extent seems like it would also provide a margin of safety given homogeneity effects eg https://www.census.gov/content/dam/Census/library/working-papers/2012/demo/SEHSD-WP2012-20.pdf https://www.census.gov/content/dam/Census/library/working-pa...