Many job seekers get nervous before interviews, and with good reason-- all the preparation in the world won't help if the interviewer isn't committed to giving the interviewee a fair chance.
According to human resources consultants, hiring managers' bad behavior can include interrupting interviews to answer phone calls, failing to take notes, acting bored or distracted,bad-mouthing their own companies, bullying applicants, or asking "gotcha" questions for no reason at all. At best, a company with a bad hiring manager will make poor hiring decisions and alienate applicants. At worst, the hiring manager could inadvertently open their company to a lawsuit by asking illegal questions.
While many companies assume that anyone can conduct an interview, it's a skill that is important for hiring managers to refine. In fact, researchers from Harvard Business School found that the worst interviewers—those who let their own insecurities or unconscious biases drive the process, for instance—can have a worse effect on hiring decisions than if a candidate were simply chosen at random.
When a hiring manager "wings it" it can cause an inconsistent interviewing experience-- which can lead to unintentional bias, and holding interviewees to unequal standards.
Instead, focus on having a script ready with interview questions, and as an interviewer, focus on your listening skills. Whether you're meeting with candidates face to face or through digital interviewing software, make sure you're judging every candidate by the same criteria, and that you're giving each a fair listen. Consider investing in a digital interview platform to help standardize your hiring practice, and make sure each of your hiring managers goes through training every once in a while to make sure that, in terms of listening skills, best practices, and the brand, everyone is on the same page.