To re-examine why you rejected them, and see if other candidates were rejected for similar reasons or not. There are several studies that show that women and minorities are simply judged harsher than their peers despite having similar levels of talent and ability[1]. Examine if perhaps you fell into that trap. Obviously if someone couldn't do fizzbuzz, they shouldn't be hired. But I would wager that in many cases, there are those candidates that are very close, and they end up getting picked or rejected based on these unconscious factors.
And, also, to look at why diverse candidates are not applying to work at your company is decent numbers.
Like my husband? "I ask every person this question, she had no idea after so much hinting. People who can't answer these questions cannot operate our code base without significant help from others. The last few times I let this slide they all turned into huge disasters. So, absolutely no. " .... HR makes someone interview this girl again to that person. This girl truly is too inexperienced to fly, but no, lets reject all these c.s degree guys with projects on their github and let's make a third person interview them again. .....God, I am a doctor, I am a minority female immigrant doctor, I don't exactly get this kind of benefit of the doubt when I look for a job, okay?
Can I give you another that I've experienced? "You rejected this interviewee? Can you give them another look? We need more diversity."
What is the proper way to proceed in this situation?