When do living wages bite?

"Many features of living wage laws may influence the strength of their effects on wages and employment of low-skill individuals. Echoing past research, business assistance living wage laws generate stronger wage increases and employment reductions than contractor-only laws. But broader enforcement or implementation and geographic concentration of living wage laws also appear to strengthen their effects. Finally, geographic concentration may be more significant than the distinction between business assistance and contractor-only living wage laws"--National Bureau of Economic Research web site.