Data Analysis best practices by Sherlock Holmes! - My Datafication

26 March, 2017

Data Analysis best practices by Sherlock Holmes!

Did you miss me? Did you miss me? Did you miss me? If you did not get the reference from the Sherlock series, check below for the episode reference (spoiler alert). As you have probably imagined, I have recently watched the Sherlock series and as a big Sherlock Holmes fan I have enjoyed the stories of the genius detective and his loyal friend Dr. Watson. What I did not realize until now though, was how many things Sherlock teaches us about data analysis. I have taken my notes about Sherlock's best practices and would like to share some of them with you.

Lesson #1: Collect the data that ARE useful

Many cases solved by Sherlock required knowledge from different scientific areas. For example, he can distinguish 140 types of cigarettes, smoking and cigars, which proves to be something extremely useful to know in some cases. Similarly, every data analyst (and user in general) can use internet as the source of any useful information. However, there are available more data and knowledge that may be useful in a case, i.e. analysis project. Thus, it is important to distinguish important and useful knowledge from useless information. Sherlock did not know that the Earth resolves around the sun, because it is not important for criminal cases. So, collect only the data that you need and remove trash data! 

Lesson #2: Deduction is reasoning backwards.

This is actually a phrase from the story, repeated many times by Sherlock in order to teach Dr. Watson about the science of deduction. In all cases, he collects the data, thinks synthetically and connects the sequence of events revealing a story with all pieces connected and justified. However, it might be easier for people to avoid situations that are difficult to explain or rely on absolute truths i.e. conventional wisdom that has never been proven to us. On the other hand, deduction does not allow such shortcuts. You have to follow the facts so that you reach correct conclusions, even if they surprise you. "When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth" (Sherlock Holmes). So, in all projects never guess! Deduct!

Lesson #3: Use FACTS to stimulate knowledge.

Similar to the Deduction lesson, Sherlock emphasizes the need to collect facts and data to reach conclusions. "It is a capital mistake to theorize before one has the facts. Insensibly, one begins to twist facts to suit theories, rather than theories to suit facts" (Sherlock Holmes). Unfortunately, there are times when people try to justify a theory using the data instead of using the data to make theories. This problem may arise  in companies if managers need justifications for their decisions, or researches if analysts try to validate theories or any other similar cases. It should be part of analysts' ethics to never use data to prove theories, but always analyze them unaffected by existing thought or theories. Data should always lead us! 

Lesson #4: Concentrate

Having collected the data and the facts, Sherlock plunges into his own world. He isolates himself in order to concentrate on the facts and build his reasoning. In our modern world, with so many distractions, it might be difficult to isolate ourselves in order to concentrate on a given analysis. However, it is important to train this skill to eliminate influences and diversion to optimize our work. Focusing 100% on one task may help identifying all useful facts and leading to the correct conclusions.
I hope you liked the article, elementary, my dear Watson! Sherlock Holmes is one of the best data analysts (or maybe the best, given that he analyzes everything using only his brain). And for sure, we could use his lessons to improve our methods and way of working. If you have read the Sherlock stories and have noticed another interesting lesson(s), please share it with me in the comment section below!

1. Sherlock Season 3, episode 3, from 1:27:24. Jim Moriarty's video where he asks 'Did you miss me?' again and again!

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  1. I guess you got your hands on IBM Watson??
    Katerina, I'm a fellow student of MSBA (AUEB) on my last year of studies.

    All my best wishes to your goal!
    U r an example that keeps my hopes for a data career abroad alive!

    1. IBM Watson! Been there, done that! But how did I forget about it while writing the post? :) Thank you very much for your comment! I wish you success, too!

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