Reliability and ValidityScale

Evaluation

Reliability Validity

Test-RetestInternal

ConsistencyAlternative Forms Construct

Criterion

Content

Convergent Validity

Discriminant Validity Nomological

Validity

Determination of Validity and Reliability

Constructs Tests Required

Reliability high

Convergent validity high

Discriminant validity low

nonsense low

Multitrait - Multimethod Matrix (Campbell & Fiske,

1959)

Method 1 Method 2 Trait a Trait b Trait a Trait b

Trait a b1 Method 1

Trait b m1 b1 Trait a va d b2

Method 2 Trait b d vb m2 b2

b1 = reliability for method 1va = convergent validity for both methods wrt trait am1 = discriminant validity for method 1d = “nonsense”-correlation

Requirements: • v > 0 and "high enough"• v > d• v > m• d low

Correlationcoefficients{

ExampleMosher Forced Choice Guilt Scale

3 traits Guilt feelings about sex Hostile guilt Guilt concerning morality

3 methods Incomplete sentences "When I dream about sex …" Forced choice

" When I dream about sex …"a) I don't remember a thing in the morningb) I feel happy when I get up

True/False "When I dream about sex I wake up feeling happy"

MTMM matrix for the Mosher Forced Choice Guilt Scale

TF(true/false)

FC(forced choice)

IS(incompl. sent.)

SG HG MC SG HG MC SG HG MCSG .91HG .52 .84TFMC .68 .50 .84SG .86 .56 .73 .97HG .53 .83 .53 .61 .96FCMC .63 .54 .83 .70 .58 .92SG .78 .51 .63 .79 .54 .57 .72HG .24 .67 .23 .33 .73 .37 .32 .65ISMC .47 .40 .66 .48 .49 .70 .49 .28 .55

Sexual

Hostile

Morality

FC very reliable, TF too, IS not

Good convergent

validity

Discriminant validity OK