If you know the work that needs to be done, it only takes two questions to determine if a candidate is knowledgeable -- and competent. Here they are.
Many years ago I received a phone call from a company owner who had heard me speak at a business leader's conference about Hiring and Getting Hired. He was clearly desperate. He implored me to remind him of the two questions I had argued would fully assess a candidate's competency for any position. He was looking for vice president of operations and I was happy to help, but before proceeding I had to ask, "So, what's the big rush?"
"The candidate is in the waiting room," he quietly confessed.
After getting briefed on his business and the position he was trying to fill, I told the owner to follow the following steps without exception:
1. Do not meet the candidate in the office. Take him for a tour of your manufacturing facility, instead.
2. As part of the tour, stop at each area experiencing a big operational problem the VP would have to address right away. In this case, these turned out to be a poor factory layout, too much scrap, and outdated process-control measures.
3. After describing each problem for a few minutes, ask the candidate, "If you were to get this job, how would you fix it?" Then have a 10-15 minute give-and-take discussion around his ideas. Based on this, evaluate the candidate on his insight, the quality of the questions, and his approach for implementing a solution.
4. Next, ask the candidate to describe something he's already accomplished that's most comparable to the problem that needs fixing. Spend another 10-15 minutes on getting specific details about this including the results and the specific changes made.
5. Ask the same two questions and follow-up the same way for the other operational problems.
6. It should take at least 90 minutes to complete the tour. When done, tell the person you're impressed with his background, and will get back to him in few days after seeing some other candidates.
A few hours later, the owner called to thank me. His insight was profound. He told me the candidate was assertive, insightful, and clearly understood the problems that needed to be solved. However, the owner said the candidate's answers to the comparable accomplishment questions were vague, shallow, and short.
He concluded the candidate was probably a great consultant or staff person, but one who couldn't be left alone in a factory. This was pretty amazing when you consider he only had a 10-minute course in interviewing under his belt.
Moral: If you know what you need done, it only takes two questions to figure out if a candidate is competent and motivated to do it. If you don't know what you need done, take a tour of the factory, and call me in the morning.