scale measures what it tested: intends to measure and is essential for the accurate Convergent construct validity was We hypothesised that the ADAS-cog and and meaningful examined by computing correlations MMSE would be highly negatively interpretation of between ADAS-cog and the mini correlated (r>-0.70) as the two scales scores.[41] mental state examination measure cognitive performance but are (MMSE[42]). scored in opposite directions. Discriminant construct validity was We predicted ADAS-cog scores should not examined by computing correlations be notably biased by these variables and, between the ADAS-cog and therefore, correlations would be low <0.30. sociodemographic variables (age and sex) to determine the extent to which they were biased by these variables. Group difference construct validity We predicted a stepwise change in was examined by comparing scores across the groups, and that the means scores would be signifincatly mean scores for the three MMSE defined groups. different.
scale measures what it intends to measure and is essential for the accurate and meaningful interpretation of scores.[41] tested: Convergent construct validity was examined by computing correlations between ADAS-cog and the mini mental state examination (MMSE[42]). Discriminant construct validity was examined by computing correlations between the ADAS-cog and sociodemographic variables (age and sex) to determine the extent to which they were biased by these variables. Group difference construct validity was examined by comparing mean scores for the three MMSE defined groups. We hypothesised that the ADAS-cog and MMSE would be highly negatively correlated (r>-0.70) as the two scales measure cognitive performance but are scored in opposite directions. We predicted ADAS-cog scores should not be notably biased by these variables and, therefore, correlations would be low <0.30. We predicted a stepwise change in scores across the groups, and that the means scores would be signifincatly different.
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