GLOSSARY

ACHIEVEMENT TEST -- a test which measures acquisition of knowledge or shill.

APTITUDE TEST -- a test used to predict success or failure in an undertaking.

COEFFICIENT OF CORRELATION -- the numerical index used to indicate the degree of correlation between two sets of paired measurements. Correlation coefficients range from + 1 for a perfect positive correlation to 1 for a perfect negative correlation.

CORRELATION -- the degree of correspondence between two sets of paired measurements.

CULTURE-FAIR TEST -- a test that avoids items in which the different experiences of various cultural groups affect the total score.

FACTOR ANALYSIS -- a statistical procedure used to identify the elements that make up any complex trait.

FREQUENCY DISTRIBUTION -- a set of scores assembled according to size and grouped into class intervals.

FREQUENCY POLYGON -- the graph in which frequencies are represented by points and points are connected by a line.

G-FACTOR -- a general ability underlying test scores. especially those of intelligence, as distinct from special or unique abilities. GIFTED CHILDREN -- children with IQ's over 130.

INTELLIGENCE -- what intelligence tests measure.

INTELLIGENCE QUOTIENT (IO) -- the ratio of a person's mental age (MA) to his chronological age (CA) multiplied by 100. 60

MEAN -- a measure of central tendency; the arithmetical average.

MEDIAN -- a measure of central tendency; the mid-point of the distribution; the point above which and below which exactly half (50%) of the scores lie.

MENTAL RETARDATION IQ below 70

MILD RETARDATION -- IQ 53-69.

MODE -- a measure of central tendency. The value that occurs most frequently.

MODERATE RETARDATION -- IQ 36-52.

NATURE-NURTURE CONTROVERSY -- the question of the relevant importance of heredity and environment in influencing human development.

NORMAL CURVE -- a bell-shaped frequency polygon

PERCENTILE -- a value on a scale of 100 that indicates the percent of the distribution that is equal to or below it. Example: a score of 85 is a score equal to or better than 85% of the scores.

PROFOUND RETARDATION -- IQ below 20.

RELIABILITY -- the degree to which repeated measures on the same subjects give the same results.

RETARDED -- anyone with an IQ less than 70.

SCATTER PLOT -- a graph that is used to show the relationship between two sets of scores.

SEVERE RETARDATION -- IQ 20-35.

VALIDITY the degree to which a test measures what it claims to measure.