Before revision: David Florence Nightingale David a sometime colleague of both Neyman and Pearson at the University College London, making a humorous aside at the end of her 1947 paper, suggested that, in the case of her own research, perhaps Neyman and Pearson's "two sources of error" could be extended to a third: Mosteller In 1948, Frederick Mosteller (1916–2006) argued that a "third kind of error" was required to describe circumstances he had observed, namely: Type I error: "rejecting the null hypothesis when it is true".
After revision: David Florence Nightingale David a sometime colleague of both Neyman and Pearson at the University College London, making a humorous aside at the end of her 1947 paper, suggested that, in the case of her own research, perhaps Neyman and Pearson's "two sources of error" could be extended to a third: Mosteller In 1948, Frederick Mosteller argued that a "third kind of error" was required to describe circumstances he had observed, namely: Type I error: "rejecting the null hypothesis when it is true".