Explain why political instability results in lower levels of economic growth.

Political instability is likely to shorten policymakers' horizons leading to sub- optimal short term macroeconomic policies. It may also lead to a more frequent switch of policies, creating volatility and thus, negatively affecting macroeconomic performance.

When an economist says that "Kevin's income elasticity of red wine is 6" he means that if Kevin's income increases by 10%, the quantity of red wine demanded by Kevin rises by 60%. So, red wine is income elastic. Since the income elasticity is greater than 1, red wine is a luxury good for Kevin.

Income elasticity measures the change in the quantity of goods demanded relative to a change in income.

If an increase in income results in a decrease in the quantity of goods demanded, then that good is an inferior or cheap good. The income elasticity of a cheap good is negative.

If the demand for a good rises with an increase in income, then that good is a normal good. The income elasticity of normal goods is greater than zero.

If an increase in income results in a greater increase in the quantity of goods demanded, then that good is a luxury good. The income elasticity of a luxury good is greater than 1.