Section Six - Cause and effect
A story about Stalin, ice cream & murder (12 minutes)
Elementary, my dear Watson!
We told you a few times that correlation does not mean causality. But what is cause and effect? Let's start with a very simple explanation (video 2.38 minutes):
Confusing cause and effect and correlation
There are different reasons that cause and effect can be confused. First, it can be just a coincidental correlation. Let's look at a very simple example.
Adolf Hitler and Josef Stalin wore moustaches, therefore wearing a moustache, makes you an immoral, genocidal dictator
Second, it can be an explainable correlation, but there is no cause and effect. In this short video (1.30 minutes) the classic example considering murder and ice cream is explained.
So, often there is a third factor to consider. In this case the warm weather.
Another example: At some British universities it was found that students that go to the gym a lot are performing better academically. Is there cause and effect? Maybe you would think so. After all, a healthy body, results in a healthy mind. Being fit gives you the energy to study hard. So, going to the gym helps you with your performance at school. Or maybe there was a third factor to consider. In this case, discipline. Disciplined students go to the gym and do well at school. Correlation, yes, cause and effect, no way.
Sometimes there is no third factor, but that still does not mean that there is cause and effect. Often there is another explanation like with the people dying in ambulances in the previous section.
There are way more examples. We will offer some in section twelve, additional materials.
Cause and effect / effect and cause?
Finally, it can be pretty hard to understand what is cause and what is effect. Let's look at some examples:
- Successful companies have satisfied employees. Or do satisfied employees lead to successful companies?
- Successful students are going to school more. Or does going to school often lead to success?
- Depressed people spend a lot of time on Instagram. Or does spending a lot of time on Instagram make people depressed?
Remember, straightforward cause-effect relationships are very attractive. They provide an easy to understand narrative, but they are also very rare.
We have found four patterns in data. These patterns are really there. But what is really happening? Is it a coincidence? Correlation? Cause and effect? Can you explain it? Download this PowerPoint Template (CC4_Data_Exercise.pptx) and think about it or discuss it (do not Google it!)
You can find the (some) answers here: CC4_Data_Exercise_Answered.pptx
Take aways from section six:
- Cause and effect is very rare;
- There is often a third factor to consider;
- Thinking in cause and effect is an attractive but deceptive narrative.