What is the total teaching staff number for Oregon,  and what is it for all those compared districts in Oregon,  and what percentage of all the teachers in Oregon are represented in those top districts?  My guess is that the eight chosen  districts have half the teaching jobs in all of Oregon.  I will also guess that those districts are used as the "comparable" for the rest of Oregon districts' teachers in collective bargaining.   Was this study about collective bargaining parity,  its raison d'être?