Hi, I just received an intercview day invitation, there is one part called Written Case, could anyone share some hints for me to prepare this kind of interview form? Many thanks!
How to prepare a written case interview?
please have a look at the following great article on Preplounge:
This gives you a good overview on what is the purpose and the main focus areas of written cases at consultancies. The best form to prepare is obviously to do as many practice cases as you can possibly do. As with the "normal" case interviews, it is a mechanical skill and muscle that needs to be built with practice.
I would recommend you to focus on 5 areas to crack a presentation/written case; I have reported them below with some suggestions on how to prepare for each of them
1. Learn how to define a plan of action and stick to that
The first thing you should do in a written case is to define a plan and allocate in the best possible way your time. Assuming 60 minutes for the analysis, a good approach would include:
- initial quick reading – 5-10 min
- structure the approach – 5 min
- make slides/answer to the questions adding detailed analysis and math – 35-40 min
- final review – 10 min
You should then practice to stick to the time allocated, in order to maximize your final performance.
2. Practice graph interpretation
You will normally have to analyse graphs in a written case. The best way to practice is to take graphs from online resources and use a timer to test in how much time you can understand the key message. McKinsey PST graphs could be a good practice for that.
3. Work on quick reading and quick understanding of key information
You will not have time to read and prioritize everything, so you have to understand where to focus. The ideal way to practice is to use long cases such as HBS ones, and practice on reducing the time needed to absorb the key information that can answer a defined question. Quick reading techniques could also help.
4. Practice quick math
You will normally have math to do in a written case. GMAT and McKinsey PST math should work well to prepare on this.
5. Learn how to communicate your slides/answers
You may have to present your findings at the end of the case. I would apply the same structures of final sum up in a live interview case, that is:
- Sum up the main questions you have to answer
- Present your proposed answer and detail the motivation behind
- Propose next steps for the areas you have not covered
As you will not be able to double check hypothesis with the interviewer as in the live case before the presentation, it could make sense to clearly state when you are making hypotheses and that you will have to verify them with further analysis.
When you have to prepare slides, quoting a previous answer I would also recommend to work on
A) structure the order of the slides
Normally the structure for a 5-slide presentation is the following:
- First slide sums up the question and provides the answer
- Second, third and fourth slide have the supporting arguments for the first slide
- Fifth slide has the next steps
B) structure the content of each slide
There are three basic components for slides:
- Chart or data
- Label for chart
Many people structure the title as the mere description of what the chart is telling. A great title, instead tells the implication of the graph. Eg say the graph is showing a cost structure for a division. A bad title would be: Cost structure from 2005 to 2015. A good title would be: Cost structure of Division XYZ is not sustainable”. A great title would be Cost structure of Division XYZ is not sustainable due to ABC, assuming you have insides on the cause. The rule of thumb for the title is that if you read all the titles of the slides together you should get a clear idea of what is going on.
C) present the slides
When you present, I would suggest the following steps for each slide:
- Introduce the slide: “Let’s move to slide 2, which will show us why we have an issue with this division”
- Present the main message of the slide: “As you can see, we have a cost structure which makes for us not feasible to be competitive in this market”
- Provide details: “The graph, indeed, shows how our fix cost is XYZ, while competitors can benefit from economies of scale. Indeed…”
Hope this helps,
I've uploaded some samples here:
(ask me for a password)
The best way to prepare is the following:
- Check if the calculator is allowed. So far it was. If not - you have to train mental math. I posted the main tips here: https://www.preplounge.com/en/consulting-forum/tips-to-do-big-multiplications-in-my-mind-726#a1422
- Prepare for a regular case interview - it helps a lot. Basically, prep lounge website is about it
- Practice making slides. Look for publically available MBB presentations for reference. Good books are "Pyramid Principle" and "How to make it with charts"
- Practice reading cases fast and prioritizing the information. I found useful two sources:
- Written cases you'll be able to find in google or in case books. I've seen a couple in "Vault Guide to the Case Interview" and "Insead Business Admission Test"
- Harvard cases - either buy or try to find online. You can find a couple of MIT cases here for free: https://mitsloan.mit.edu/LearningEdge/Pages/Case-Studies.aspx Unfortunately free cases don't have the prep questions.
The appropriate structure for BCG written case is:
Slide 1: Context, Objective, Recommendations
Slide 2-4: Analysis (Usually 1 slide with a table, 1 slide with graphs and 1 slide with pros and cons)
Slide 5: Next steps or risks & mitigation