Happy, by what percentage

For some reason I ended up watching some documentary about Myalgic encephalomyelitis. I’ve not enough knowledge on the subject to make any opinion.

But what struck me was how a sufferer managed to equate the level of depression following certain treatments. One made her about 40% less depressed; whilst another made her about 50% less depressed.

Just how the heck can anyone work that out? I don’t know about you, but I don’t think I can tell if I’m 10% less happy one day to the next.

I’ll be 8% more informed if you could drop me a quick email to let me know how this all works. Thanks.