week 11 applied scale construction Flashcards
(42 cards)
construct vallidity
does a questionnaire actually measure what its proponents claim to measure
what are 2 steps to establish validity
- necessary steps for validity to be present, but not validity itself
- validity its self
precautions for validity
discrimination, reliability and structure
what does Pearsons r show
the extent/correlation in which 2 scores tend to go together
also measures direction of their link - or +
systematic error
a potentiallly knowable bias, pushing scores one way or another
random error
bias in no particular direction
5 standard sateps to achieve construct validity for a questionnare
- item design
- item analysis - to achieve discrimination
- reliability analysis - to achieve reliability
- factor analysis - to achieve structure
- scale validation
SD
direct measure of dispersion of variability or variation in scores.
the higher the better
skew
a direct measure of asymmetry or imabalnce in a distribution of scores
absence of skew is the best
what is scale reliability
consistency
consistency between items is called
internal consistnecy
consistency over time is called
test-retest reliability
consistency between scores is called
inter-rater reliability
what does rho represnet
real correlations in a population
how is internal consistency represented
alpha 0-1
a goof item should have an average inter-item correlation of
greater than or equal to r=.20
a good item shouls have an item-total correlation of
greater than or equal to r=.30
how is overall reliability measured
coefficient or Cronbach’s alpha
a barely acceptbale alpha is
0.60
a good alpha exceeds
0.90
a factor is
a single underlying dimension
factor analysis
the technique used to show that a scale, which is meant to measure one construct, measures one construct—or to find out how many it happens to measure.
FA reduces…
variances across many variables to fewer distinct clusters of shared variance
3 stages of FA
factor extraction
factor rotation
factor interpretration
