According to the latest research by economists, when the annual income is below 10,000 dollars, as the family income increases, the happiness of family members will increase significantly. However, once the annual income reaches more than 10,000 dollars, even if the economy continues to prosper and family income continues to increase, the happiness of family members will increase slowly.
According to the above definition, which of the followings can be inferred?
Research shows that there is no direct relationship between happiness and money.