reflective vs. formative models

Reflective Model 

Items <-- Construct 

e.g.

Construct: Drunkeness 

- uncoordinated walking 

- glossy eyes 

- vomiting 

(items are related) 

Formative  Model 

Items --> Construct 

- Beer 10 liter 

- Vodka 1 liter

- Wine 1 liter 

(unrelated )

Therefore, formative measures define, produce, or cause the construct rather than vice versa !