From "Are Emily and Greg More Employable Than Lakisha and Jamal

From "Are Emily and Greg More Employable than Lakisha and Jamal? A Field Experiment on Labor Market Discrimination" by Marianne Bertrand and Sendhil Mullainathan
The authors conduct a field experiment to determine if stereotypical ethnic and non-ethnic sounding names in resumes as well as return mailing addresses constitutes a perceived proxy for race, and, thus, constitutes racial discrimination in job applicant "callbacks." The authors find it likely that a form of discrimination operates at all occupational levels and credentialing statuses.
-Discuss the ways the authors experimentally "manipulate" their design to increase the probability that they are assessing whether discrimination exists.