concurrent validityThe extent to which test
scores correlate with scores on other relevant
measures administered at the same time.
construct validityThe extent to which test
scores correlate with other measures or behaviors
in a logical and theoretically consistent way.
Construct validity requires a demonstration of all
aspects of validity.
content validityThe degree to which test items
adequately measure all aspects of the construct of
interest.
crystallized abilityOne of two higher-order
factors of intelligence conceived by Cattell. Crystal-
lized ability refers to the intellectual capacities
obtained through culture-based learning.
deviation IQA concept introduced by Wechsler
to address problems observed when applying the
ratio IQ to older individuals. An individual’s
performance on an IQ test is compared to that of
her or his age peers.
dizygotic (DZ) twinsFraternal twins, or twins
that share about 50% of their genetic material.
equivalent-forms reliabilityThe extent to
whichanindividualobtainssimilarscoreson
equivalent, or parallel, forms of the same test.
fluid abilityOne of two higher-order factors of
intelligence conceived by Cattell. Fluid ability
refers to a person’s genetically based intellectual
capacity.
Flynn effectThis refers to the empirical finding
that Americans’IQ scores have on average
increased 3 points each decade since 1972.
gThe term introduced by Charles Spearman to
describe his concept of a general intelligence.
genotypeThe genetic makeup of an individual.
Index scoresScores that correspond to the major
ability factors that underlie the WAIS-IV subtest
scores (i.e., Verbal Comprehension, Perceptual
Organization, Working Memory, and Processing
Speed).
intelligenceThere is no universally accepted
definition of intelligence. However, many defini-
tions of intelligence emphasize the ability to think
abstractly, the ability to learn, and the ability to
adapt to the environment.
intelligence quotientA term developed by Stern
in 1938 to address problems with using the
difference between chronological age and mental
agetorepresentdeviance.Typically,adeviation
IQ score is used.
internal consistency reliabilityThe extent to
which the items of a test“hang together”(most
often assessed by computing Cronbach’salpha).
interrater (or interjudge) reliabilityThe level
of agreement between two or more raters who
have evaluated the same individual independently.
Agreement can refer to consensus on behaviors,
attributes, and so on.
mental ageA term introduced by Binet as an
index of mental performance. This idea was based
on the notion that individuals of a certain age
should have mastered certain abilities.
monozygotic (MZ) twinsIdentical twins, or
twins that share 100% of their genetic material.
phenotypeThe observable characteristics of an
individual. The phenotype is a product of both the
genotype and the environment.
predictive validityThe extent to which test
scores correlate with scores on other relevant
measures administered at some point in the future.
Primary Mental AbilitiesSeven factors of
intelligence derived by Thurstone on the basis of
his factor analytic work: Number, Word Fluency,
Verbal Meaning, Perceptual Speed, Space, Rea-
soning, and Memory.
reversal itemsA feature on several subtests of the
WAIS-III that allows the examiner to determine
the examinee’s ability level without having to
administer items markedly below that ability level.
split-half reliabilityThe extent to which an
individual’s scores on one half of a test (e.g., the
even-numbered items) are similar to his or her
scores on the other half (e.g., the odd-numbered
items).
stability of IQ scoresThe similarity of IQ
scores measured at different points in time.216 CHAPTER 7