Not many candidates finish a CS PhD in three years. Four is probably the mean, with three and five being the typical upper and lower ranges. Often the funding

Not many candidates finish a CS PhD in three years. Four is probably the mean, with three and five being the typical upper and lower ranges. Often the funding dries up after three years, but the student soldiers on anyway because they're well past the point of no return, or because their advisor can employ them in some other capacity like a teaching or research assistant.