The external component refers to the validity with which meaning can be attributed to the numerical values.
MOT was completely insensitive to this aspect of biological motion, suggesting the MOT is sensitive to the extent to which groups of dots can be segmented into one object, but not to the naturalness or ecological validity with which that object moves.
Likewise, the dynamics of HIV-related mortality over time – a complete epidemic curve at the Agincourt, South Africa, site and sharp declines from epidemic peaks in other high-prevalence settings – supported the validity with which InterVA-4 was identifying HIV-related deaths.
On the other hand, a consequence of the reduction of items is a loss in content validity, the comprehensiveness with which each domain is sampled, and investigators must be cognizant of this issue when they reduce the number of items [ 12].
According to a recent review [ 60], insufficient evidence exists (only 2 poorly controlled RCTs with questionable external validity, within which only a small subgroup of women met the inclusion criteria) to recommend the use of anti-thrombotic agents in women with unexplained recurrent pregnancy losses without anti-phospholipid antibodies.
Another major subitem of validity is internal validity, which deals with the cause effect relationships, eg, the impaired nutritional status leads to poor outcome, and the nutritional support improves outcome, independent of the effect of the underlying disease.
Other aspects of criterion validity are convergent validity, which refers to an agreement with an already established method (≈sensitivity), and concurrent validity, which refers to not falsely identifying groups of subjects without the condition (≈specificity).
From this perspective, arguers aim to construct "cogent arguments that are convincing in virtue of their intrinsic properties and with which validity claims can be redeemed or rejected" (ibid., 25).
The available designs vary in terms of their goals, their claims to internal and external validity, and the ease with which they are feasible to execute given the stubborn realities of inner and outer contexts of healthcare.
Different terms are used in the literature to describe validity, and in this context, discriminant validity refers to the degree with which the instrument discriminates between groups with known differences, and convergent validity refers to the degree to which two theoretically related measures of construct are actually related.
It includes convergent validity and divergent validity, which can be assessed by examining the pattern of correlations with other variables.
