Chapter 3: The Measurement of Behaviour Flashcards
Psychometrics
The study of psychological measurement.
Converging Operations
Measuring a construct in several different ways (e.g. combining observational, physiological, and self-report measures).
Nominal Scale
Numbers assigned are simply labels for characteristics or behaviour (e.g. Males = 1, Females = 2).
Ordinal Scale
The rank ordering of people’s behaviours or characteristics (students’ ranking from lowest to highest in a class). An ordinal scale does not tell us the distance between participants on the variable being measured.
Interval Scale
Equal differences between the numbers reflect equal differences between participants, but there is no true zero point (e.g. scores on an IQ test).
Ratio Scale
Equal differences between the numbers reflect equal differences between participants, and there is a true zero point (e.g. weight).
Observed Score
True Score + Measurement Error
True Score
The score that a participant would have obtained if the measure were perfect and we were able to measure without error.
Measurement Error
Variability in scores due to factors that distort the true score.
Five Sources of Measurement Error
- Transient States: A temporary, unstable state of the participant (e.g. mood).
- Stable Attributes: Enduring traits of the participant (e.g. illiteracy).
- Situational Factors (e.g. characteristics of the researcher or research setting).
- Characteristics of Measure (e.g. ambiguous wording).
- Mistakes in Recording a Participant’s Score
Reliability
The consistency or dependability of a measuring technique. Usually expressed as a correlation coefficient.
Correlation Coefficient
Expresses the strength of the relationship between two measures.
Test-Retest Reliability
Consistency of participants’ responses on a measure over time.
Interitem Reliability
Assesses the degree of consistency among the items on a scale. Tells us whether all of the items on a scale are measuring the same thing. If not, summing scores across the items creates measurement error and lowers reliability.
Item-Total Correlation
The correlation between a particular item and the sum of all the other items on the scale (ideally > .30).
Split-Half Reliability
Divide the items on a sccale into two sets and examine the correlation between the sets.
Cronbach’s Alpha Coefficient
Equivalent to the average of all possible split-half reliabilities (adequate if > .70).
Interrater Reliability
The consistency among two or more researchers who observe and record participants’ behaviour.
How can we increase the reliability of measures?
- Standardize administration of the measure.
- Clarify instructions and questions.
- Train observers.
- Minimize error in coding data.
Validity
The degree to which a measurement procedure actually measures what it is intended to measure rather than measuring something else (or nothing other than error).
Face Validity
The extent to which a measure appears to measure what it’s supposed to measure.
Construct Validity
The extent to which a measure of a hypothetical construct relates as it should to other measures.
Convergent Validity
A type of construct validity that assesses the extent to which a measure correlates with other measures that it should correlate with (e.g. embarrassability should be positively associated with shyness but negatively correlated with self-confidence).
Discriminant Validity
A type of construct validity that assesses whether a measure does not correlate with other measures that it should not correlate with (e.g. embarrassability should not correlate with IQ).
Criterion-Related Validity
The extent to which a measure allows us to distinguish among participants on the basis of a particular behavioural criterion. Researchers examine whether behavioural outcomes are related to scores on the measure as expected.
Concurrent Validity
A type of criterion-related validity that assesses the extent to which scores on a measure are related as expected to a criterion that is assessed at the time the measure is administered (e.g. an embarrassability scale administered today predicts blushing in the current situation).
Predictive Validity
A type of criterion-related validity that assesses the extent to which scores on a measure are related as expected to a criterion that is assessed in the future (e.g. an embarrassability scale administered today predicts whether students sign-up for public speaking classes next semester).
Test Bias
Occurs when a particular measure is not equally valid for everyone.
