Shooting in the dark here, but I imagine dose size is an important variable in a study like this. At 500mg, I'm pretty sure a member of the LDS* could tell the difference between coffee and cocaine.
[*] I'm only calling out the LDS community here because they don't consume coffee, or cocaine, generally speaking.
Mormon tea / ephedrine is not commonly consumed and as far as I know it isn't consumed at all by LDS faithful. It's just a silly colloquial name for a plant.
But, due to a lot of retroactive canon gymnastics, cold caffeinated beverages like soda are consumed in great quantities by Mormons. Actually, under the latest "official" stance, tea made from the "mormon tea" plant would actually be banned, as it's a "hot beverage" with mental effects.
[*] I'm only calling out the LDS community here because they don't consume coffee, or cocaine, generally speaking.