In addition, Kreiss and McGregor’s (2019) research suggests that internal
negotiations over ad policies within the ﬁrms are also important. For example,
sales team representatives within a ﬁrm like Facebook may advocate for their
political clients with their colleagues on the policy team, helping ad sponsors by
shaping the interpretation of particular policies (Kreiss and McGregor 2019).

how digital advertising is purchased and why it matters
for research

In addition to the regulatory challenges of tracking and analyzing digital
advertising, the decentralized way in which advertising is purchased online
represents an enormous hurdle to understanding the universe of online and
social media advertising. Some digital advertising is purchased directly from the
source on which it will appear (e.g., a local mayoral campaign in Denver may go
directly to the Denver Post to purchase advertising on its website just as
Social_Media_and_Democracy