concurrent validity

the extent to which one measurement is backed up by a related measurement obtained at about the same point in time. In testing, the validity of results obtained from one test (e.g., self-report of job performance) can often be assessed by comparison with a separate but related measurement (e.g., supervisor rating of job performance) collected at the same point in time. See also criterion validity.

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Psychology term of the day

January 27th 2025

hydrogen-ion concentration

a measure of the acidity or alkalinity of a substance. When acid and alkaline substances dissociate in water, hydrogen ions (H⁺) and hydroxyl ions (OH^–) are released. Acidity and alkalinity are associated with the relative concentrations of H⁺. The hydrogen-ion concentration can be measured using the pH scale, on which values represent the negative logarithm of the H⁺ ion concentration. Thus, the greater the excess of H⁺ ions, the lower the pH value. A pH of 0 represents the greatest possible excess of H⁺ ions, or a “pure” acid. At the other extreme, a pH of 14 represents the maximum degree of alkalinity. A pH of 7 represents a neutral solution. Human body fluids have an average pH of about 7.4, that is, slightly alkaline. If the pH rises above 7.8 or falls below 6.8, enzymes and other biochemical substances in the body malfunction (see acidosis; alkalosis). See also homeostasis.