Interviewing is not a science. Nor is it an art form. It is simply an imperfect form of human communication designed to increase the predictive validity of potential employer-employee relationships. And it is very imperfect.
There are basically eight types of questions you may face during the course of your interview:
Credential verification questions
This type of question includes "What was your GPA?" and "How long were you at _____?" Also known as resume verification questions. Its purpose is to objectively verify the depth of knowledge of the credentials in your background.
Experience verification questions
This type of question includes "What did you learn in that class?" and "What were your responsibilities in that position?" Its purpose is to subjectively evaluate features of your background.
This type of question includes "What would you do in this situation?" and "What are your strengths and weaknesses?" Its purpose is to subjectively analyze how you would respond in a series of scenarios. The reality is that Tape #43 in your brain typically kicks in ("I know the answer to that one!") and plays back the pre-programmed answer.
This type of question includes "Can you give me a specific example of how you did that?" and "What were the steps you followed to accomplish that task?" Its purpose is to objectively measure past behaviors as a predictor of future results.
This type of question includes "Can you give me a specific example of your leadership skills?" or "Explain a way in which you sought a creative solution to a problem." Its purpose is to align your past behaviors with specific competencies which are required for the position.
This type of question includes "What is 1000 divided by 73?" to "How many ping pong balls could fit in a Volkswagen?" to complex algorithms. Its purpose is to evaluate not only your mental math calculation skills, but also your creative ability in formulating the mathematical formula for providing an answer (or estimate, as can often be the case).
This type of question includes problem-solving questions ranging from: "How many gas stations are there in Europe?" to "What is your estimate of the global online retail market for books?" Its purpose is to evaluate your problem-solving abilities and how you would analyze and work through potential case situations.
This type of question includes "What kind of animal would you like to be?" and "What color best describes you?" Their purpose is to get past your pre-programmed answers to find out if you are capable of an original thought. There is not necessarily a right or wrong answer, since it is used primarily to test your ability to think on your feet.
Interviewing is a game in which I deal the cards, but you can stack the deck by preparing in advance. Then it's up to you to play the cards in the best way possible.
It is interesting to note that the first three types of interview questions listed have a predictive validity for on the job success of just 10 percent. And 10 percent predictive validity is the same level that is generated from a simple resume review. Brainteaser questions increase the predictive validity to 15 percent (since they test intelligence, commonly a key competency for most positions) and case questions raise the predictive validity to 25 percent (and slightly higher for consulting positions). Behavioral and competency interviewing, on the other hand, yield a predictive validity of 55 percent. Still far from perfect, yet much more reliable for most interviewers. Interestingly, the first three question types are still the favored approach by most untrained interviewers, simply due to lack of experience. Behavioral and competency interviewing is gaining greater acceptance by trained interviewers because past performance is the most reliable indicator of future results, especially when it is tied to the specific competencies for the position.