Why did it take so long to desegregate schools after the brown v. board of education decision?

This is the answer With Brown v. Board the Supreme Court ruled against segregation for the first time since reconstruction. ... In declaring school segregation as unconstitutional, the Court overturned the longstanding “separate but equal” doctrine established nearly 60 years earlier in Plessy v. Ferguson (1896).

Your data would be better.

The reason is because the data you have made depending on where you sourced or measured your data it's most likely going to be more reputable then your friends but it's good to compare data sets if you are both working on the same thing.