Interviewer feedback is critical to making a hiring decision, so Google's hiring team gives interviewers the following guidance to write helpful feedback and avoid common pitfalls:

• Don’t write vague statements or summarize the resume. Statements like "seems smart" or "graduated from a great school" won't help hiring committees make a decision.
• Don’t reiterate info from the rubrics. The rubrics contain the bulk of your assessment. For example, in "Underwater Basket Weaving," when you check the "Excellent" box you're telling the committee that your candidate did things like clearly incorporate efficient use of material into basket planning. So explain more in your comments -- give examples instead of restating information.
• Don’t get distracted by personality and "fit" or evaluate attributes unrelated to the job. Stay focused on the key attributes that make someone successful in the role.
• Don’t procrastinate. Write interview feedback as soon as possible, while it's still fresh in your mind.

In Google's hiring process, this feedback is then passed to the hiring committee to inform their decision. Since no one on the hiring committee actually interviews the candidate, they’re entirely beholden to the written feedback they receive. Our hiring committees will provide “feedback on feedback,” letting interviewers know if their feedback was helpful, too long, too short, or if they should be focused differently.