Glossary D
Glossary D
Discrete variable is defined as a variable whose attributes are separate from one another, or discontinuous, as in the case of gender or religious affiliation. Contrast this with Continuous variable s, in which one attribute shades off into the next. Thus, in age (a continuous variable), the attributes progress steadily from 21 to 22 to 23, and so forth, whereas there is no progression from male to female in the case of gender.
Discriminability is generally defined as the ability to distinguish between one stimulus and another. In the Recognition-by-components theory of object perception, Discriminability is a property of geons, which indicates that each geon can be distinguished from other geons from almost all viewpoints. In item analysis, Discriminability is how well an item performs in relation to some criterion. For example, items may be compared according to how well they separate groups who score high and low on the test. The index of discrimination would then be the correlation between performance on an item and performance on the whole test.