Mathematical formula. It concerns the length of a test and its reliability. An increase in items will increase reliability. [Charles dward Spearman (1863-1945), British psychologist and psychometrician; W. Brown, 20th-century British psychologist! Spearman rank order correlation. See rank order correlation. [Charles Spearman|
SPEARMAN-BROWN PROPHECY FORMULA: "The Spearman-Brown prophecy formula looks at the reliability of tests."