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A nephelometer [1] or aerosol photometer [2] is an instrument for measuring the concentration of suspended particulates in a liquid or gas colloid. A nephelometer measures suspended particulates by employing a light beam (source beam) and a light detector set to one side (often 90°) of the source beam.
Test validity is the extent to which a test (such as a chemical, physical, or scholastic test) accurately measures what it is supposed to measure.In the fields of psychological testing and educational testing, "validity refers to the degree to which evidence and theory support the interpretations of test scores entailed by proposed uses of tests". [1]
Symptom and attitude tests are more often called scales. A useful psychological test/scale must be both valid, i.e., show evidence that the test or scale measures what it is purported to measure, [1] [4]) and reliable, i.e., show evidence of consistency across items and raters and over time, etc.
Reliability is supposed to say something about the general quality of the test scores in question. The general idea is that, the higher reliability is, the better. Classical test theory does not say how high reliability is supposed to be. Too high a value for , say over .9, indicates redundancy of items.
For example, Galton measured strength of grip and height and weight. He established an "Anthropometric Laboratory" in the 1880s where patrons paid to have physical and physiological attributes measured. Galton's measurements had an enormous influence on psychology. Cattell continued the measurement approach with simple measurements of perception.
Reliability does not imply validity. That is, a reliable measure that is measuring something consistently is not necessarily measuring what is supposed to be measured ...
Health psychology is a discipline that understands the psychological, behavioral, and cultural aspects that affect the physical health and illnesses within individuals. A psychologists with the focus of health psychology would have a biopsychosocial model approach with patients.
The most recent edition of the Sixteen Personality Factor Questionnaire (16PF), released in 1993, is the fifth edition (16PF5e) of the original instrument. [25] [26] The self-report instrument was first published in 1949; the second and third editions were published in 1956 and 1962, respectively; and the five alternative forms of the fourth edition were released between 1967 and 1969.