Perhaps you should try some spelling variations:
social effect » social effects, societal effect, special effect
effect model » effect models, effects model, effects models
social rats » social rates, social rate, social etats
rats model » rat model, rate model, ratio model

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (( social effect model ) OR ( social rats model ))*.