VALIDITY AND RELIABILITY
VALIDITY: REFERS TO THE RELATIVE ACCURACY, TRUTHFULNESS, OR CORRECTNESS OF THE STATEMENT
VALIDITY - TYPES:
1. INTERNAL VALIDITY
2. EXTERNAL VALIDITY
3. CONSTRUCT VALIDITY
4. STATISTICAL VALIDITY
TYPES OF VALIDITY
INTERNAL VALIDITY:
THERE IS SOUND REASON TO BELIEVE THAT A CAUSE-EFFECT RELATIONSHIP EXISTS BETWEEN THE INDEPENDENT AND DEPENDENT VARIABLE (IV CAUSES DV)
CONFOUNDING VARIABLE:
ERROR THAT OCCURS WHEN THE EFFECTS OF TWO VARIABLES IN AN EXPERIMENT CANNOT BE SEPARATED, RESULTING IN A CONFUSED INTERPRETATION OF RESULTS (EX. POVERTY AND RACE (IVS) PREDICTING IQ).
EXTERNAL VALIDITY:
THE EXTENT TO WHICH A SET OF RESEARCH FINDINGS PROVIDES AN ACCURATE DESCRIPTION OF WHAT TYPICALLY HAPPENS IN THE REAL WORLD (CAN YOU GENERALIZE YOUR FINDINGS TO OTHER PEOPLE?).
STATISTICAL VALIDITY:
THE EXTENT TO WHICH DATA ARE SHOWN (THROUGH STATISTICAL METHODS) TO BE THE RESULT OF CAUSE-EFFECT RELATIONSHIPS RATHER THAN BY ACCIDENT.
TESTS AND QUESTIONNAIRES
CONSTRUCT VALIDITY:
A TEST SHOULD MEASURE WHATEVER THE THEORETICAL CONSTRUCT IS AND NOT SOMETHING ELSE (SHOULD MEASURE THE CONCEPT YOU ARE TRYING TO TEST).
CRITERION VALIDITY:
THE TEST SHOULD CORRELATE WITH OTHER MEASURES OF THE SAME THEORETICAL CONSTRUCT (IF THE TEST MEASURES IQ, IT SHOULD CORRELATE/BE RELATED TO OTHER TESTS OF IQ).
CONCURRENT VALIDITY:
TWO DIFFERENT BUT RELATEDMEASURES CORRELATE TOGETHER (SCHOOL PERFORMANCE CORRELATES WITH IQ)
PREDICTIVE VALIDITY:
MEASURE PREDICTS FUTURE PERFORMANCE (I.E., ACT SHOULD PREDICT FUTURE GRADES IN COLLEGE).
FACE VALIDITY:
LOOKS LIKE IT TESTS WHAT IT TESTS (THE QUESTIONS GIVE IT AWAY)
CONTENT VALIDITY:
THE TEST SHOULD SAMPLE THE RANGE OF BEHAVIORS REPRESENTED BY THE THEORETICAL CONCEPT BEING TESTED (THE ITEMS SHOULD ALL ADD TO WHAT THE OVERALL TEST INTENDS TO MEASURE).
RELIABILITY
THE CONSISTENCY OR REPEATABILITY OF A MEASURE OR AN OBSERVATION.
INTEROBSERVER AGREEMENT/INTERRATER RELIABILITY:
THE DEGREE TO WHICH DIFFERENT JUDGES INDEPENDENTLY AGREE UPON AN OBSERVATION OR JUDGEMENT (GETTING MORE THAN ONE OPINION).
INTERNAL CONSISTENCY:
PROVIDES INFORMATION ABOUT THE DEGREE TO WHICH ALL OF THE SPECIFIC ITEMS OR OBSERVATIONS IN A MULTIPLE ITEM MEASURE BEHAVE THE SAME WAY (THE ITEMS SHOULD ALL CONTRIBUTE TO THE OVERALL CONCEPT THAT THE TEST IS MEASURING).
TEST-RETEST RELIABILITY:
THE DEGREE TO WHICH AN ITEM OR A SCALE CORRELATES POSITIVELY WITH ITSELF OVER TIME (DOES THE TEST PERFORM THE SAME AT TIME ONE AS IT DOES AT TIME TWO?).
MUNDANE AND EXPERIMENTAL REALISM:
INCREASES EXTERNAL VALIDITY
EXPERIMENTAL REALISM:
DEGREE TO WHICH A RESEARCH STUDY IS REALISTIC OR PSYCHOLOGICALLY MEANINGFUL TO THE PARTICIPANTS.
MEASUREMENT SCALES
CHARACTERISTICS OF RELATIONS AMONG NUMBERS ASSIGNED TO OBJECTS.
NOMINAL SCALE:
CATEGORICAL
INVOLVES MEANINGFUL BUT POTENTIALLY ARBITRARY AND NONNUMERICAL NAMES OR CATEGORIES.
EXAMPLE: GENDER (1,2)
ORDINAL SCALE:
INVOLVES RANKING OR ORDER
EXAMPLE: TROPHIES (1ST PLACE, 2ND PLACE, 3RD PLACE).
INTERVAL SCALE:
ALLOWS US TO MAKE QUANTITATIVE STATEMENTS ABOUT THE MAGNITUDE OF THE DIFFERENCES BETWEEN OBJECTS.
EXAMPLE: F. OR C. SCALES
RATIO SCALE:
SINGLE UNIT DIFFERENCES ON THE RATIO SCALES ALWAYS HAVE THE SAME VALUE OR MEANING ALL ALONG THE POSSIBLE POINTS OF THE SCALE.
** HAS A TRUE ZERO POINT
EXAMPLE: WEIGHT