The study looked at the relationship between income and spending of rural residents in Hebei Province from 1983 to 2007. They found that income and spending have a stable connection over time. In the short term, income affects spending, but this effect weakens over time. Spending doesn't have an immediate impact on income, but it becomes significant over time. Increasing income can boost spending in the short term, while expanding domestic demand can drive economic growth in the long term.