  The Sloan Digital Sky Survey (SDSS) is one of the largest international
astronomy organizations. We present demographic data based on surveys of its
members from 2014, 2015 and 2016, during the fourth phase of SDSS (SDSS-IV). We
find about half of SDSS-IV collaboration members were based in North America, a
quarter in Europe, and the remainder in Asia and Central and South America.
Overall, 26-36% are women (from 2014 to 2016), up to 2% report non-binary
genders. 11-14% report that they are racial or ethnic minorities where they
live. The fraction of women drops with seniority, and is also lower among
collaboration leadership. Men in SDSS-IV were more likely to report being in a
leadership role, and for the role to be funded and formally recognized. SDSS-IV
collaboration members are twice as likely to have a parent with a college
degree, than the general population, and are ten times more likely to have a
parent with a PhD. This trend is slightly enhanced for female collaboration
members. Despite this, the fraction of first generation college students (FGCS)
is significant (31%). This fraction increased among collaboration members who
are racial or ethnic minorities (40-50%), and decreased among women (15-25%).
SDSS-IV implemented many inclusive policies and established a dedicated
committee, the Committee on INclusiveness in SDSS (COINS). More than 60% of the
collaboration agree that the collaboration is inclusive; however, collaboration
leadership more strongly agree with this than the general membership. In this
paper, we explain these results in full, including the history of inclusive
efforts in SDSS-IV. We conclude with a list of suggested recommendations based
on our findings, which can be used to improve equity and inclusion in large
astronomical collaborations, which we argue is not only moral, but will also
optimize their scientific output.
