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
Assesses
Time sampling error
Test-Retest reliability
Alternate or Parallel Form reliability
Internal Consistency reliability
Assesses
Internal consistency error
Assesses
Item sampling error
Test-Retest Reliability
Judging Internal Consistency
Correlation Matrix
Q9
Q10
Q17
Q18
Scale
Q9
Q10
Q17
Q18
I
I
I
I
Scale
Mean
if Item
Deleted
Q9
Q10
Q17
Q18
1.0000
.1829
.1888
.1730
1.0000
.5718
.4031
1.0000
.5302
1.0000
Corrected
Variance
if Item
Deleted
ItemTotal
Correlation
Anxiety Scale Items
am carefree
8.9250
8.4753
.2220
am rarely9.4750
overcome 9.
with
6.2272
worries
.5460
I am
carefree
am not a 9.2875
worrier
5.3720
.6160
10.
I
am
rarely
overcome
with
rarely feel
9.1750
fearful or anxious
6.8804
.5141
.0494
.3452
.4367
worries
.2999
17. I am not a worrier
18. I rarely feel fearful or anxious
Reliability Coefficients
Alpha =
Squared
Multiple
Correlation
.6846
4 items
Standardized item alpha =
.6749
Alpha
if Item
Deleted
.7513
.5655
.5080
.5930
 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
ConstructValidity
Validity
Divergent Construct
Correlations
Our measure of extraversion Correlations
HEIGHT
SHOE
EXTRA202
1.000
-.066
should not
be HEIGHT
correlated
be correlated
withwith
NEOEXTRA .843**
CLASSEXTRA
NEO
Extravers
ion Scale
SHOE
.477**
.843**1.0001.000
.011
things unrelated
related
to extraversion
to extraversion
Class
ClassExtraversion
ExtraversionScale
Scale
1.000
-.066 .477**.011
1.000
**.
**.Correlation
Correlationisisssignificant
ignificantatatthe
the0.01
0.01level
level(2-tailed).
(2-tailed).
Assessing Construct Validity
Convergent
ConstructValidity
Validity
Divergent Construct
Correlations
Correlations
Our measure of impatience
HEIGHT
should be
notImpatience
correlated
be correlated
with
Scale
‘02 with
SHOEto impatience.
Impatience
‘03
things related
unrelated
toScale
impatience.
HEIGHT ‘02 SHOE
EXTRA202
‘03
1.000 1.000 .857**
-.085
.275*
.857** .275*1.000
.039
1.000
Impatience Scale
-.085level (2-tailed).
.039
1.000
*. Correlation is significant at the 0.05
**. Correlation is significant at the 0.01 level (2-tailed).
 Testing

Utility of Psychological Tests

Reliability




Alternate or Parallel Form
Internal Consistency
Test-Retest
Validity



Content
Criterion-Related
Construct