For graduate student purposes, The Department is not so important as The Area. Our Department is huge, so huge that it is divided into Areas that have little to no interaction with each other; I couldn't even tell you how many there are, let alone their names. So, even though therea re ~4,000 undergraduates in our Department, it only feels like there are 12-20 graduate students.
enter 2004: 5 start, 4 now (drop out post-master's)
enter 2005: 3 start, 2 now (drop out 2nd year)
enter 2006: 5 start, 4 now (drop out 1st year)
The trend of dropping out earlier and earlier is probably a result of small sample size (I only know about the years immediately around mine), and has to reverse since most of the "enter 2007" class seems to be here (I can't remember if there are more than 4 now, let alone at the beginning of the school year). In the big picture, our attrition rate probably doesn't seem too bad.There are always going to be those who decide grad school isn't for them, or just get sick of it after so many years.
From the very immediate perspective of being one of those who entered in 2005, however, both class size and attrition have tremendous psychological impact. Especially since the two of us who remain have the same advisor. This was great in the "Have you scheduled your defense yet? Oh good, because I haven't either..." sense, but bad in the "Did you know we had to have this paperwork in by today??? Our advisor didn't mention it!" sense.
Now, our paths diverge. The first post-master's step is to propose our comps paper by April (3rd year), and defend it by December (3rd year). But the other student is doing a double major, and gets a one-year extension on the defense. We propose at the same time, but he with the sense of "oh, I've got plenty of time to work on the actual paper". What little support network I have in navigating the deadlines and/or milestones of progress to a PhD will be gone.
On the bright side, most (all?) of the students in the year above me are also double-majoring, and will be defending their comps at my deadline. One of these is also in my lab, so I have a near-neighbor to commiserate with. As long as I can overcome that sense that they had two years to put together these papers, and I only had one, so can I possibly do as good a job? On the whole, I would have preferred connections to the larger Department, or at least more students in my year.