as mentioned by Vlad, you won't need a completely different approach for interviewer-led cases compared to interviewee-led cases. The main difference between the two is that in interviewer-led cases, the interviewer will lead you though 4 to 6 different areas in the case. On the other hand, in an interviewee-led case, the interviewer may be silent for the whole case and just provide information when asked. As a consequence, the main distinction is related to the communication you have to keep during the case, and not, say, the structure to present initially, the way to interpret graphs or the way to present your final sum up.
More specifically, in an interviewer-led case I would recommend to pay attention to the following communication elements. These elements are also important in an interviewee-led case, although to a lower degree, since, as mentioned, the kind of communication with the interviewer will be different as he/she may simply provide answers to your question.
- Repeat all the questions asked. You will move quickly in different areas, potentially not yet structured in your initial framework. It is thus very important that you clarify well the questions before proceeding and be sure you are answering to the right one. Missed clarification of the question is one of the main sources of mistakes I see in interviewer-led cases.
- Communicate clearly your structure, articulating in first and second layers, for each question. Many candidates think they can stop to structure in an interviewer-led case after the initial structure and proceed with pure brainstorming when asked, for example, 5 ways to increase revenues. That’s a mistake, as you should always have a MECE first layer for every question asked, and then a second layer to go deeper.
- Follow the interviewer’s suggestions. If you are moving though a tangent, or the interviewer simply wants you to focus on a specific point for the next area, it is very likely he/she will try to move you back to the “right” direction. The usual way to do so is asking if you are not forgetting anything, or what do you think about a particular different path. You should take the hint and try to understand what else you should have considered. Some candidates keep focusing on their structure only, thus showing they are not listening to the interviewer, and lose points due to that.
You should not transform the case in a candidate led one, as the interviewer will not allow for that anyway; however you can definitely be proactive in your approach. For example, when commenting a graph, you could conclude stating which are the next steps and asking a followup question to proceed, eg:
“It seems that the problem relays in the cost of labour of blue collar workers in 50-60 year-old range; it would be interesting to understand if there is any way to make the process more efficient and (i) decrease the number of workers, or (ii) try to find a way to decrease the cost of each worker. Do we have any information whether one of these two things was tried in the past and how we perform compared to competitors on them?”.
The interviewer will very likely bring you to another area, potentially different from the ones you mentioned. That doesn’t mean you have structured incorrectly, and you will score points for being proactive; you should then follow the path presented from the interviewer to proceed.
Hope this helps,