A rubric breaks a role into the criteria that matter, such as customer handling or shift flexibility, and describes what a weak, adequate and strong answer looks like for each. Scorers then match each answer to the closest description rather than giving a general impression. For example, a strong answer on handling a complaint might name the problem, the action taken and the result, while a weak one stays vague.
Rubrics make scores comparable across interviewers, days and large applicant pools, and they make it possible to explain why one candidate ranked above another. They work best when built from the job description and agreed with the hiring manager before screening starts. Reviewing a sample of scored answers from time to time helps catch criteria that are unclear, irrelevant or applied unevenly.