The join type between the USAspending File B and the GAO Cost Summary files is a left outer$-$

join, because there are records in the DATA Act data that do not have corresponding program

activity codes. The program activity code is the linking field between the two files. The outer$-$join

is necessary to retain $100\%$ of the spending data. The remaining joins between File B and the OMB

object class descriptions and between the object class descriptions and the major object class files

are the typical inner$-$joins where the data is consistent across each file.