The experimental methods used in the study of the personal equation were later accepted by the emerging field of psychology  which developed strong (full factorial) experimental methods to which randomization and blinding were soon added.
ðɪ ɛkspˌɛɹɪmˈɛntəl mˈɛθədz jˈuːzd ɪnðə stˈʌdi ʌvðə pˈɜːsənəl ᵻkwˈeɪʒən wɜː lˈeɪɾɚɹ ɐksˈɛptᵻd baɪ ðɪ ɪmˈɜːdʒɪŋ fˈiːld ʌv saɪkˈɑːlədʒi wˌɪtʃ dɪvˈɛləpt stɹˈɔŋ fˈʊl fæktˈoːɹɪəl ɛkspˌɛɹɪmˈɛntəl mˈɛθədz tʊ wˌɪtʃ ɹˌændəmᵻzˈeɪʃən ænd blˈaɪndɪŋ wɜː sˈuːn ˈædᵻd.