A push or a pull is a force. Forces can make things move, change their speed, or change their shape. We cannot see a force but we can see its effects. Look at this toy car. It isn’t going anywhere.

Steele, F., Washbrook, E., Charlton, C. and Browne, W.J. A longitudinal mixed logit model for estimation of push and pull effects in residential location choice. Choice of residential location ...