The Interviewing Formula

The final installment of my hiring process series. For the full series here.

In my senior year at Clemson University I sent out my resumes to every employer in the Career Center database that had anything to do with machine design. I knew that I wanted to design machines. I scheduled an interview with a company. The interview had two parts, the standard ‘tell me about a time…” questions (Behavioral Interview Questions) and a practical test where I was given some problems and asked to work them out. The interview went very well. This is not my opinion, the interviewer told me so. He told me that I did very well, I had solved the problems with more ease and completeness than anyone he had seen in a long time, including the other engineer from Clemson that they were going to bring in for a second onsite interview. At this point I was feeling good about my chance for a second interview, which is why I was so shocked when he continued and said I would not be getting a second interview and wished me luck. I asked why and he said that my GPA was too low, and the other guy had a 4.0.

I did not have the best grades in college. I was a B/C student with a 2.8. Luckily for students like me companies like Google are starting to realize that GPA does not indicate success in a job. I was entering the job market a little too early for this trend to help me out. I did end up getting a job in design and have loved it and believe myself to be successful. I have had a long tenure with a large company and been given increasing responsibility through the years, so I assume others think I am good at what I do as well. This interview was my first exposure to the problem of hiring. I knew I was going to be good because I understood the fundamentals of engineering, I had a passion for machine design, and I am hard working. But how does a company see that?

I have spent most of my career at one company. It is large, has a lot of resources and I think it is a great place to work. The problem is it does not have much name recognition in the general population. With the subset of students that want a career in Oil & Gas the top talent gravitates to the companies that have their logos above gas stations. My second exposure to the problem of hiring was how do I identify the people that are going to be great but are passed over by the top names because of interviewing practices, like the one described above.

For the rest of this article I am going to lay out my strategy for talent identification during an interview process. During the years that I have implemented this strategy, I have not had a single miss on the person I hired. I will explain my process from an engineering perspective, but I believe that this method can be used for any position and produce great results. First you need to extend your interview time frame. Finding the right person takes time and is worth it. The only thing worse than having an opening is filling that opening with the wrong person.

I believe the proper formula for an interview consists of hospitality, behavioral interview questions, and skills assessment. You can mix the ratios to fit the type of job you are filling. While this interview formula will evolve over time, it is important that it stays the same for each batch of interviewees. The questions should be presented in exactly the same way each time. After the position is filled, go back and evaluate what went well and what can be improved. Remember to ask for feedback from the person you hired, they typically have valuable insight.


Hospitality is first in the ratio for a reason. When the prospective employee shows up, do your best to make them comfortable. Thank them for coming in, offer them something to drink, coffee, water, (tea if you have it), show them where the restroom is, and offer breaks in between sessions. This is a small step but goes a long way to improve their ability to perform, as well as want to accept an offer. It is easy to see the person you are interviewing as ‘needy’ and wanting something from you. But the reality is, a job is a mutually beneficial business relationship. The interviewee has arranged their schedule and gone to sometimes great personal inconvenience to go through this interview process. I don’t think it unreasonable to meet them with a warm welcome, a hot cup of coffee, and some personal consideration. Welcome them like you would if they were a guest in your home.

Behavioral Interview Questions

There are a ton of resources showing you how to ask Behavioral Interview Questions. Your HR department likely has guidance or just a simple Google search will give you better advice than I can. Do not shortchange these. I will say that these questions can tell you a lot about the character of the person you are interviewing but not everything you need to know. However, as it has been covered extensively in other places, I will leave it alone.

Skills Assessment

The best way to assess skills is using them. At my company we design machinery, so I have written two questions that cover the bulk of the skills required to do the job well. This is not a written assessment; it is a conversation. The first question is a simple design, one we have already completed. We present the problem and ask the interviewee to walk us through concept, analysis, manufacturing, and installation. We ask questions, push for more detail, and challenge assumptions. We have a whiteboard with plenty of markers to facilitate the conversation. The second question is a root cause analysis. We present a real failed part and some details on how it is used. The question is, why did it fail and then what we do about it. Again, challenging assumptions, pressing for details, and sketches on the whiteboard. We typically allow 30 minutes to answer each question. There is no ‘gotcha’ tricks or hidden traps. We cannot present everything required to solve the problem, so we invite questions. We score this on the quality of the questions asked of us, the understanding of the concepts being discussed, and the understanding of the business of engineering. We don't count off for not having an encyclopedia level of knowledge of thing that can easily be looked up. Do you know the yield strength of 17-4 stainless steel in the H1150 condition off the top of your head? I don't but, I know where to look it up.

You will need to have someone experienced enough to carefully judge the answers, as well as someone with the discipline not to interject or put words in the candidate’s mouth but being encouraging and open to new solutions. It is also critical that the questions you are asking are related to past projects. Interviewing people is not the time to try and squeeze out free consulting services.

It is critical that you believe in your interviewing. If a person passes the behavioral questions with flying colors and cannot intelligently discuss engineering problems, do not hire them. If a person is brilliant in the engineering discussion and the behavioral questions expose character flaws, do not hire them. Do not be afraid to interview lots of people. We typically run 10 people through this in-depth interview formula for each hire. We break it up into teams and have an interview rotation to help with the time. Each interviewee spends 4 hours with us. So, we are looking at least 40 hours of interview time per position. But it is worth it, since implementing this system, we have not had a single hire turn out to be something other than what we thought they were.