psychological testing principle types of psychological tests mental ability tests intelligence –...
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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 errorAssesses
Internal consistency error
Test-Retest Reliability
Q9 Q10 Q17 Q18
Q9 1.0000Q10 .1829 1.0000Q17 .1888 .5718 1.0000Q18 .1730 .4031 .5302 1.0000
Correlation Matrix
Scale Scale Corrected Mean Variance Item- Squared Alpha if Item if Item Total Multiple if Item Deleted Deleted Correlation Correlation Deleted
Q9 8.9250 8.4753 .2220 .0494 .7513Q10 9.4750 6.2272 .5460 .3452 .5655Q17 9.2875 5.3720 .6160 .4367 .5080Q18 9.1750 6.8804 .5141 .2999 .5930
Reliability Coefficients 4 items
Alpha = .6846 Standardized item alpha = .6749
I am carefreeI am rarely overcome with worriesI am not a worrierI rarely feel fearful or anxious
Judging Internal Consistency
Anxiety Scale Items
9. I am carefree10. I am rarely overcome with worries17. I am not a worrier18. 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
Correlations
1.000 .477**
.477** 1.000
NEO Extraversion Scale
Class Extraversion Scale
NEOEXTRA CLASSEXTRA
Correlation is significant at the 0.01 level (2-tailed).**.
Our measure of extraversion should be correlated with things related to extraversion
Divergent Construct Validity
Correlations
1.000 .843** -.066
.843** 1.000 .011
-.066 .011 1.000
HEIGHT
SHOE
Class Extraversion Scale
HEIGHT SHOE EXTRA202
Correlation is significant at the 0.01 level (2-tailed).**.
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
1.000 .857** -.085
.857** 1.000 .039
-.085 .039 1.000
HEIGHT
SHOE
Impatience Scale
HEIGHT SHOE EXTRA202
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 .275*
.275* 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