A scale where all items are intercorrelated
Uni-dimensional scale
Scale with sub-scales which are weakly correlated
Multi-dimensional scale
Four Types of Reliability
1) Internal consistency
2) Test-retest
3) Alternate forms
4) Inter-rater
Internal Consistency
Consistency amongst items
Test-retest
Consistency over time
Alternate forms
Consistency over equivalent versions
Inter-rater
Consistency over observers/raters