I feel like you can come up with a solution without going that far. If you're willing to forego multi-select, anyway. Create multiple 'cause of LE' fields (set form rules to only display 2nd cause if 1st cause is populated, etc). Create a (hidden) formula field that's an inverse of the count of non-empty cause fields. Then have your reporting sum the weights by matching cause. Would that work?
Not sure if there's a way to keep the multi-select field and parse out the individual selections into a formula field, I've avoided working with multi-select fields for similar reasons... but I imagine not, as if there was, I guess Mark would have suggested it.
Or, if there are a fairly manageable number of different causes, you could go another route and create formula checkbox fields for each cause, using CONTAINS against the multi-select field (does CONTAINS(ToText([multi-select])) work?) to check them, another field to invert the count of the checked causes, and then sum those weights in reporting.
EDIT: Bless the 'Related Conversations', Mark has already written a formula to part out multi-select fields:
https://community.quickbase.com/quickbase/topics/trying-to-count-the-number-of-selections-in-a-multi...So you don't need to know the names of the causes to do it, then - just the maximum number of causes that might be selected. If it's, say, 5, create 5 fields to use that Part formula to store the individual causes selected, another field to invert the count of the non empty of those, and Bob's your uncle.
