I want to know how race affects the consideration of job applicants. I have 20 men make appointments for advertised managerial jobs at the same 10 companies. Half of them are African American and half are white. They use the same resumes and have been trained to respond to questions in the same way. I measure the number of job offers each group gets to determine whether race had any effect on job offers. In this study a control condition was

1.race.
2.the credentials of the applicant.
3.number of job offers.
4.time of day of the interviews.