validity and reliability

Split-half reliability

The degree of agreement when a test is split in half and the reliability of first half is compared to the second half; a measure of internal consistency of an instru¬ment.

Reliability

The degree to which a test consistently measures what it is intended to measure.

Predictive validity

The degree to which a test is able to predict future performance.

Construct validity

The degree to which a test measures an intended hypothetical abstract concept (non-observable behaviors or ideas).

Content validity

The degree to which an instrument measures an intended content area.

Validity

The degree to which an instrument measures what it is intended to measure.

Intrarater reliability

The degree to which one rater can obtain the same rating for a given variable on multiple measurement trials; an individual's consistency of rating.

Internal validity

The degree to which the observed differences on the dependent variable are the direct result of manipulation of the independent variable, and not some other vari¬able.

External validity

The degree to which the results are generalizable to individuals (general population) or environmental settings outside the experimental study.

Test-retest reliability

The degree to which the scores on a test are stable or consistent over time; a measure of instrument stability.

Concurrent validity

The degree to which the scores on one test are related to the scores on another criterion test with both tests being given at relatively similar times; usually involves comparison to the gold standard.

Interrater reliability

The degree to which two or more independent (raters can obtain the same rating for a given variable; the consistency of multiple raters.

Placebo effect

subjects respond to a sham treat¬ment with positive effects

Threats to Reliability

1. Errors of measurement

Experimenter bias

Expectations of the researcher; about the expected outcomes of the study influence the results of a study.

Failure to exert rigid control over subjects and conditions

Intervening variables interact with the dependent variable

Face validity

The assumption of validity based on the appearance of an instrument as a rea¬sonable measure of a variable; may be used for initial screening of a test instrument but psy-chometrically unsound.

selection bias

The researcher introduces systematic sampling error,

Sampling bias

The researcher introduces systematic sampling error,

Hawthorne effect

The subject's knowledge of par¬ticipation in an experiment influences the results of a study.