The equation doesn't have measurable units but instead represents the proportions and relationships of the variables. Any other study or article that uses some formula may or may not be a good idea, I can't speak for anyone else, but I think this form allows me to say the most in the least amount of space. (By contrast, there was a study going around recently that spoke about the "formula for happiness," with the "equation" using what seemed like 10 variables and tons of complex notation that seemed to probably take more work to use than to simply write it out).

Re: Anxiety approaching zero, it's not intentional because you can end up in a tangential argument about what feeling amounts to "zero anxiety" then claiming that should make your head explode because the equation is undefined, so I'd rather offer an alternate form just to try to avoid spending time on that. Having said though, in paper 2 we mention Nitrous Oxide which seems to lower anxiety beneath our natural levels and has the side effect of making people laugh at all kinds of inappropriate and abnormal things. So artificial lower of anxiety DOES seem to amplify the overall humor people feel.