Class summary 9/26

* Child quantity ----------> Child quanlity

* "Coordination" :    Rich family: send child to school to get better education for better future
                                     Poor family: stay at home or on farm doing work

* Fertility rates ------ replacement rates

* Technology ------> improved productivity
                                               higher wages
                                               more training
                                               technology
* Peer effect : our decision is effected somehow by environments.

* Institution (social concepts) : we arrange with others to make our life more tolerable
( Respect for the rule of law)