How to interpret charts and data in case interviews
It is almost guaranteed that during case interviews with McKinsey, BCG, or Bain, you will be handed one or more charts or data tables containing valuable information for the problem solving process and your recommendation in the end.
Charts visually represent data in the form of points, bubbles, lines, bars, and pies amongst others. Tables contain data in an organized manner. Using both tables and charts can display values measured in a company (e.g., sales data), in a market (e.g., market growth), etc. Specific types of charts are better suited than others for different uses. However, during the case interview, you are often not presented with the best available or most suitable chart format.
Many candidates struggle with this part of the case interview. In fact, being able to quickly skim through a wide range of data, elicit the key information and derive top-down what it means for the question at hand is a key skill that all major consulting firms are looking for in candidates.
The goal of StrategyCase.com is to provide you with the necessary case interview secrets, habits, and tricks. You can train this skill and improve your analytical approach to data tables and graphs and along the way improve your overall performance in the case. In order to interpret charts most effectively and find their ‘so-what’ to impress the interviewer, here are a few habits you should internalize and apply whenever you are asked to interpret some data in the form of tables, graphs, etc.
Zero in on the key bits of information
To interpret a table or chart, read the title, look at the units and labels, then derive the key insight. Study the graph to understand what it shows within 15-30 seconds. Not all information on the papers you get is insightful or important and some might even be misleading. Parts of the information hidden in the charts is crucial, others just create noise to distract you. Often they contain decoys that trick you into faulty conclusions or logic.
The key is to filter out the one or two key messages, most striking when looking at it first. There will always be other things you could infer but in the interest of time, that would likely not be relevant for the case recommendation (think 80/20).
The key messages hidden in the data and charts is usually one of the following:
- Some number or group of numbers is very small or very large compared to the others (internal vs. market, internal vs. specific competitor, internal vs. other internal,…)
- Some number or group of numbers show high growth or low growth compared to the others
- There is a specific trend or trend reversal
- There is a specific relationship or (negative) correlation between two or more numbers
- There are absolute or relative changes in one value vis-a-vis some comparable values
- On average, the numbers look good, however, when digging deeper into specific segments we see certain issues or deviations
Make sure to spot those kinds of patterns quickly. When you are given two or more charts/ tables the key insight usually comes from combining both.
Whenever you present an insight during a case interview you should communicate your findings top-down. The same is true when presenting your interpretation of a chart, table, graph, etc. Start with the single most important fact you can extract from the chart.
- Give the answer or the key insight the interviewer is looking for
- Then, provide supporting evidence in a logical sequence. Substantiate your findings with strong arguments from the data. You want to build one or more pyramids with the findings on top and the facts that substantiate it as the base.
- Discuss the ‘so-what’ for the client problem you are trying to figure out and find a recommendation for. Tie those findings to the case and your analysis and interpret their implications.
Don’t start going in circles; don’t go astray. Stay structured and hit the interviewer with the key points. The interviewer mimics the client and senior clients usually don’t have much time to spare. Every sentence in the chart interpretation part should add value to your analysis. Stay away from empty words and phrases or worse aimless rambling.
By setting your communication up that way, you demonstrate that you are able to
- Are able to retrieve key insights in a data set quickly
- Communicate top-down with senior executives
- Consider the impact of the data on the current issue
Also, you give the interviewer a chance to dig deeper to understand your reasoning. In that case, you could present more details fitting your train of thought.
Avoid common pitfalls
Stay away from the following common pitfalls and you will already fare better than 80% of case interview candidates we have interviewed.
- Starting to talk about the data without prior thinking, basically figuring out insights along the way without proper structure
- Quickly finding the insights, but then keep rambling on until the interviewer has to step in and ask the candidate how to proceed
- Failing to recognize or mixing up units and magnitudes, especially across charts and tables
- Failing to properly identify the units, labels, and different axes
- Failing to interpret the key insights in the context of the case at hand
- Lacking a proper so-what of the key insights and not explaining the implications of the data
- Messing up computations along the way (see here for our guide on case interview math)
Train chart interpretation
You can quickly improve your chart interpretation skills by applying the case interview tips above. Prepare for McKinsey, BCG, and, Bain case interviews by analyzing charts in magazines such as The Economist or the Wall Street Journal. To check your insights, compare them with the text short articles accompanying the charts.
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