| criterion-related validity | The degree of effectiveness with which performance on a test or procedure predicts performance in a real-life situation; e.g., a good correlation between a score on an intelligence test such as the Scholastic Aptitude Test and one's 4-year college grade point average. (05 Mar 2000) |
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| Rayleigh criterion | <microscopy> A criterion chosen by Lord Rayleigh to define the limit of resolution of a diffraction-limited optical instrument. It is the condition that arises when the centre of one diffraction pattern is superimposed with the first minimum of another diffraction pattern, produced by a point (or line) source equally bright as the first. For a microscope under this condition, a 26.5% dip in brightness appears between the two maxima, giving rise to the sensation (or probability) of twoness. See: Abbe limit, Sparrow limit (of resolution). (05 Aug 1998) |
| criterion | A standard by which something may be judged. Origin: Gr. Kriterion = a means for judging (18 Nov 1997) |
| suydam stability criterion | <physics> A criterion for the stability of modes localised arbitrarily close to a mode-rational surface in a circular cylindrical geometry. See: rational surface. (19 Jan 1998) |
| Lawson criterion | <physics> Scientific breakeven criterion based on the product of energy confinement time and particle density. Together with plasma temperature, the Lawson value of a plasma indicates how close it is to self-sustained (ignited) fusion. See: ignition. (09 Oct 1997) |
| validity | 1. The extent to which a measurement, test or study measures what it purports to measure. 2. Occasionally, accuracy. (18 Nov 1997) |
| concurrent validity | An index of criterion-related validity used to predict performance in a real-life situation given at about the same time as the test or procedure; the extent to which the index from one test correlates with that of a nonidentical test or index; e.g., how well a score on an aptitude test correlates with the score on an intelligence test. (05 Mar 2000) |
| construct validity | The extent to which a test or procedure appears to measure a higher order, inferred theoretical construct, or trait in contrast to measuring a more limited, specific dimension; e.g., a sychrony in the scores on the Stanford-Binet Test, on a test of information processing, and the rate of glucose metabolism in the brain all are indices of intelligence. (05 Mar 2000) |
| content validity | The extent to which the items of a test or procedure are in fact a representative sample of that which is to be measured; e.g., items relating to ability in arithmetic and defining words are appropriate content for an intelligence test. (05 Mar 2000) |
| predictive validity | Criterion-related validity used to predict performance in a real-life task at a future time. See: construct validity, criterion-related validity. (05 Mar 2000) |
| face validity | The extent to which the items of a test or procedure appear superficially to sample that which is to be measured. (05 Mar 2000) |