week2-crux-questions-feedback.html
Week 2 Crux Questions - Feedback
|
1. Use the stock and flow model approach to describe the difference between positive feedback and negative feedback.
|
Comments the question called for a simple definition using stock and flow icons and then a comparison the point of the stock and flow is to be able to describe interactions such as this in specific terms if the stock declines and the flow declines, that actually a positive feedback control (imagine the opposite direction of stock change for the same control) the stock will increase with increased flow - that's not positive feedback, it's the information link that makes it a feedback control |
| 2. Use stock and flow model language to describe how some human populations may get caught in the "poverty trap" with increasing populations and decreasing wealth per capita.
How is this related to the traditional "demographic transition" that proceeds to steady state populations in post-industrial countries?
|
Comments everything you said is true but you were supposed to describe it in terms of the stock and flow approach, which allows you to highlight positive and negative feedback and steady state societies don't complete the fertility transition unless the wealth per capita is sufficient to support those activites (education etc.) - Demographic transition takes place over a long time. It doesn't hold for countries that lapse into poverty recently due to wars or climate disasters. For example, the death rate decrease is compared to the situation in which there was very little medical or sanitation. the post-industrial transition in population growth rate took place because individuals chose to have smaller families - it wasn't a plan of the government to reduce population The right answer is in there, but you should make a better connection between the poverty trap description and the transition in phase 3 of the demo trans.
|