Calculating a treatment effect is then trivial: "the effect of any treatment is estimated by taking the difference between the mean of the observations which receive the treatment and the general mean".
kˈælkjʊlˌeɪɾɪŋ ɐ tɹˈiːtmənt ɪfˈɛkt ɪz ðˈɛn tɹˈɪvɪəl: "ðɪ ɪfˈɛkt ʌv ˌɛni tɹˈiːtmənt ɪz ˈɛstᵻmˌeɪɾᵻd baɪ tˈeɪkɪŋ ðə dˈɪfɹəns bᵻtwˌiːn ðə mˈiːn ʌvðɪ ɑːbzɚvˈeɪʃənz wˌɪtʃ ɹᵻsˈiːv ðə tɹˈiːtmənt ænd ðə dʒˈɛnɚɹəl mˈiːn".