Graphical Exercises Variables that shift the AD curve: a. Increase in interest rate b. Increase in government purchase c. Increase in expectation about future income d. Increase in exchange rate Variables that shift the AS curve: a. Increase in productivity b. Increase in labour force or capital stock c. Increase in expected future price level Critical Thinking skill question Briefly explain whether investment spending is likely to increase more rapidly in a country with a rapidly growing population or in a country with a slowly growing population. Does your answer depend on whether the country is a high income industrial country or a low income developing country