Psychological Testing

Principle Types of Psychological Tests  Mental ability tests Intelligence – general Aptitude – specific  Personality scales Measure motives, interests, values, and attitudes

Key Concepts in Psychological Testing  Standardization Test norms Standardization group  Reliability Correlation coefficient  Validity Content validity Criterion-related validity Construct validity

Classical Test Theory  Goal of testing is to identify subject’s “true score” on a given attribute. Classical Test Theory says… Test Score=True Score+Error of Measurement Goal of test developers is to minimize this!

Sources of Measurement Error  Where do these measurement errors come from? Item sampling error Internal consistency error Time sampling error Random error

 Testing  How do psychologists know how well their test is measuring a person’s true score? By assessing test reliability Test-Retest reliability Internal Consistency reliability Alternate or Parallel Form reliability Assesses Time sampling error Assesses Item sampling error Assesses Internal consistency error

Test-Retest Reliability

Q9 Q10 Q17 Q18 Q Q Q Q Correlation Matrix Scale Scale Corrected Mean Variance Item- Squared Alpha if Item if Item Total Multiple if Item Deleted Deleted Correlation Correlation Deleted Q Q Q Q Reliability Coefficients 4 items Alpha =.6846 Standardized item alpha =.6749 I am carefree I am rarely overcome with worries I am not a worrier I rarely feel fearful or anxious Judging Internal Consistency Anxiety Scale Items 9. I am carefree 10. I am rarely overcome with worries 17. I am not a worrier 18. I rarely feel fearful or anxious

 Testing  How do psychologists know their test is measuring what they think it is measuring? By assessing test validity  Content validity  Criterion-related validity  Construct validity

Fig. 9-4, p. 339

Fig. 9-5, p. 340

Assessing Construct Validity Convergent Construct Validity Our measure of extraversion should be correlated with things related to extraversion Divergent Construct Validity Our measure of extraversion should not be correlated with things unrelated to extraversion

Our measure of impatience should not be correlated with things unrelated to impatience. Correlations ** ** HEIGHT SHOE Impatience Scale HEIGHTSHOEEXTRA202 Correlation is significant at the 0.01 level (2-tailed). **. Assessing Construct Validity Convergent Construct Validity Our measure of impatience should be correlated with things related to impatience. Divergent Construct Validity Correlations * *1.000 Impatience Scale ‘02 Impatience Scale ‘03 ‘02‘03 Correlation is significant at the 0.05 level (2-tailed). *.

 Testing  Utility of Psychological Tests Reliability  Alternate or Parallel Form  Internal Consistency  Test-Retest Validity  Content  Criterion-Related  Construct