Why might government expenditures be more appropriate than tax cuts to counter recessions? Is there any evidence for this thinking?

According to the traditional Keynesian model government expenditures have a larger impact on aggregate demand than tax cuts. Since tax cuts will be partly saved, the impact of a tax cut on aggregate demand is less than the impact of an increase in government expenditures. There is some evidence from computer simulations that government expenditures have a larger multiplier effect than tax cuts.