Shifts of the curve occur because of changes in factors 1,2,3,4 and 6. Productivity of future capital. If the productivity of capital is high, the return from investment is higher and I will be higher. The real interest rate. At lower rates of interest, firms will invest more since borrowing costs will be lower.
Corporate taxes lower the after-tax return from investment and reduce the amount of investment.
Shifts along the curve occur because of changes in r. Shifts of the curve occur because of changes in factors 1 and 3. Public savings increase as the increase in T reduces the budget deficit. Therefore, the fall in private savings is smaller than the increase in taxes. The result in labor markets is lower wages and slightly less employment.