My colleague and I just did an interview today (separately) for the same position. The interviewers asked her very basic simple questions, nothing technical or analytical. The position itself requires a lot of data sorting in Excel and analytical work to interpret, analyze the data and to produce recommendations to improve processes.

I was bombarded with situational questions relating specifically to the job and my qualifications in respect to Excel and accounting; after all it is a financial analyst position.

She was just asked if she knows how to use Excel and her background. No accounting related questions. No situational questions either.

The difference between the two of us is that I am very far ahead of her in terms of accounting knowledge and experience. She comes from a non business background.

Why do interviewers ask different questions? Why interview people who are not even qualified for the job? Is this just general procedure they go through?

As a former hiring exec for an international employment agency I will tell you I did it because each person/situation is different. I'm sure there were some similarities, however I would have to see both resumes to drill down to specifics on the situational etc. If she has more job experience and less education than you that might explain the situational questions. They may want to ensure you could handle the decision making requirements of the job. Without as much work experience I would wonder about your decision making skills. Hope this helps

Sorry, forgot to answer the procedural questions too.

YEs it is procedure to ask different questions.

As far as determining if a person is qualified that is the purpose of an interview. That data cannot be extrapolated from a resume alone. Hence one of the problems in today's marketplace, the inability of hiring personnel to effectively evaluate potential hires due to high amounts of cross positional skill sets available today.

Sometimes employers will ask questions based on the information you've provided in your resume. If you have experience with Excel and data analysis then that's what they would be interested in.

There would be no pint asking the other person theses questions if they don't have the experience.

Apart from that, the structure of the interview should be similar so that they can benchmark and assess your responses and performance.

Generally speaking they are supposed to structure the interview the same way for all candidates so that they can compare and also so that it's a fair process. Sometimes I will drill down further with a candidate on their experience or qualifications as I'm interested to see how much they know. It could just be that your colleague didn't have ask much to be asked about.
One tip from me - when doing an interview don't focus on the "opposition". The only person's performance you can influence in this person is your own so make sure you give it your best shot and are prepared.
Hope you got the job.