The severity of clinical illness was evaluated through the psychophysics method of magnitude estimation. The purpose of this experiment was: 1) to compare the scales derived from right judgement (magnitude estimation) used in three different Brazilian samples; 2) to verify the stability and agreement of severity estimations of clinical situations judged in Brazil, USA and England. In order to develop this study, professionals who work in the areas of psychology, nursing and medicine were invited. The lower coefficient of Pearson's correlation among the groups were of 0,88 the and the greater of 0,94. The exponents found between the Brazilian and American samples were of 1,22 and between the Brazilian and English samples of 1,15.
severity of diseases; magnitude estimation; psychophysics
