Full spectrum? Energy efficient? 25/40/60/75 or 100 watt? Is the light bulb being changed north or south of the equator? What day is it and what time zone? And finally (well, probably not finally) are we in a good mood or a bad mood while changing said lightbulb seeing as this has a direct impact on how many people it will take.
Definitions of good mood and bad mood are debated in other threads.
JJ
p.s. Full moon or no?