There are several contributing factors. One is that CollegeScorecard only includes grads who are in the federal database (usually Pell grants) for a small number of years (may be only single year). This leads to a small sample size at many colleges, which is not representative of the full student body. This can artificially create a larger variation in median salary than actually occurs. The small sample size leads to some colleges being reported much higher than actual, and others being reported much lower than actual.
The 2nd and often more influential factor is CS salary shows a large correlation with location. The colleges that have the largest portion of students working in very high cost of living areas, such as Silicon Valley or Seattle, tend to have the highest starting salaries. At some colleges, nearly all grads move to very high cost of living areas after graduating. However, at most colleges, a good portion of graduates do not choose to work in very high cost of living areas, which contributes to why they show lower salaries.
I’ll use Brown and GATech as an example. Brown shows the 2nd highest CS tax reported earnings on the list at $185k, while GATech shows a much lower $110k. I think most would say GATech is a better college in CS than Brown, and GATech students probably have better experience on average than Brown with one the highest rates of co-ops in the US, probably the highest. So why do GATech grads have so much lower earnings than Brown grads?
Looking at their respective post-graduate surveys, GATech’s survey shows by far the largest portion of CS grads work in the state of Georgia – 149 in the most recent year. Florida is the 2nd most common location at 11. However, the number working in California is too small to list for privacy reasons. None work in Seattle. GATech grads tend to be Georgia residents who have family/friends in GA and prefer to live in GA after graduating. Few choose to move to very high cost of living areas like Silicon Valley or Seattle after graduating. ’
In contrast looking at the Brown post graduate survey, nearly every CS grad chooses to work in very high cost of living areas – Silicon Valley, Seattle, NYC, or Boston. For all practical purposes nobody chooses to remain in state. The comparison might be more similar to Brown’s >$150k (small sample size boosts some colleges and hurts others, Brown likely was a boosted college) for grads that choose to work in very high cost of living areas vs GA Tech’s $110k for grads that choose to remain in Georgia.
This can have implications on a student’s goals after graduation. If the student would like to remain in Georgia, GATech is probably going to better assist with that goal. For example, there are going to be a lot more GA companies at career fairs than would occur at other colleges, more opportunities for internships or special networking at GA companies, etc. In contrast, if you want to work in a very high cost of living area (SV, Seattle, NYC, or Boston); Brown is likely to have a good representation of companies at career fairs and may have special connections at out of state companies.