Brief Summary
This video explains why correlation does not imply causation, a fundamental concept in psychology. It covers four key reasons why we can't assume that one thing causes another just because they are related: the post hoc fallacy (assuming causation based on timing), the directionality problem (not knowing which variable influences the other), the third variable problem (a hidden variable affecting both), and confirmation bias (seeing patterns that confirm pre-existing beliefs). The video uses relatable examples to illustrate each concept and emphasizes the importance of critical thinking when interpreting relationships between variables.
- Correlation does not equal causation.
- Post hoc fallacy: Assuming A causes B simply because A happened before B.
- Directionality problem: Unclear which variable is influencing the other.
- Third variable problem: A hidden variable is affecting both observed variables.
- Confirmation bias: Seeing patterns that confirm pre-existing beliefs, leading to illusory correlations.
The video introduces the concept that correlation does not imply causation, highlighting how our brains tend to seek patterns and connections, often leading to the assumption that one thing causes another. The presenter uses the example of wearing a crystal necklace and experiencing better sleep to illustrate how we might mistakenly attribute cause and effect without proper evidence or a control group. The video aims to explain why we cannot establish causality from a correlation, even when two things appear to be related.
The presenter emphasizes that observing a relationship between two variables does not automatically mean one causes the other. The video will explore four key reasons why we cannot definitively establish causation from correlation alone. This sets the stage for a deeper examination of potential pitfalls in interpreting relationships between variables.
The post hoc fallacy, or "after this, therefore because of this," is explained as the assumption that because event A occurred before event B, A must have caused B. Examples include sports superstitions, like wearing the same socks for every game, and the misconception linking vaccines to autism due to the timing of vaccinations and autism diagnoses. The presenter clarifies that correlation does not equal causation.
The directionality problem arises when two variables are related, but it's unclear which one is influencing the other. For example, poor sleep is related to stress, but it's uncertain whether poor sleep causes stress or stress causes poor sleep. Similarly, exercise and happiness are linked, but it's unclear if exercise leads to happiness or if being happy makes one more likely to exercise. Without knowing the direction of influence, causality cannot be established.
The third variable problem, also known as a confounding or lurking variable, occurs when an unforeseen factor connects two seemingly related variables. The example of ice cream sales and shark attacks is used to illustrate this point; both increase during summer heat waves, making it appear as though there's a relationship between them when, in reality, a third variable (summer) is responsible for both. Another example is family dinners being correlated with students doing well in school, where the third variable is general parenting style.
Confirmation bias, the tendency to seek out information that confirms pre-existing beliefs, can lead to the perception of causation where only correlation exists. The presenter uses the example of a doctor believing that a full moon causes chaos in the hospital, when in reality, the hospital might be equally chaotic during other phases of the moon. This leads to illusory correlations, where we see relationships between things when there is none, such as full moons and chaos, vaccines and autism, or sugar and hyperactivity.
The video recaps the four reasons why correlation does not imply causation: timing issues (post hoc fallacy), uncertainty about the direction of the relationship (directionality problem), the presence of a lurking variable, and the influence of our own biases. These factors can lead us to incorrectly establish causality when two variables are merely related.
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Transcript
Full transcript of “Correlation vs Causation I Explained”. Click a timestamp to open the video at that moment. Need another video? Use the YouTube transcript generator.
0:00 I recently read a study that as ice cream sales increase so do the number of shark techs does that mean that ice cream is causing people to get bit by sharks should we have a national ban on ice cream or could there be another explanation lurking beneath the [Music] surface whenever I see that two things are closely related my brain jumps to conclusion that one of those things is likely the cause of the other this is because my brain naturally looks for patterns and Connections in the world I can't leave anything to chance or Randomness there must be a reason or explanation for everything take for example our scenario ever since I started wearing a crystal necklace I haven't had any trouble sleeping and on
0:47 the surface our brain thinks this must be a very spiritual a very powerful necklace because it helped me sleep right cause and effect a cause B but in reality we have not had a control group we've not done experimentation we cannot say that one calls the other we can either asay that they are related or most likely they are just coincidental right there's just kind of randomness of why you're sleeping probably has nothing to do with a necklace so in this video we're going to tackle that big phrase in Psychology ready correlation does not imply causation just because two things are related does not mean one cause the other we're going to dive into four key explanations of why we cannot establish causality from a correlation all right let's start with the first one a post ha FY this is a fancy way of saying a
1:32 occurred then B occurred therefore a caus b this is on the basis of timing right if we see an event in the world we think whatever happened just right before it must have been the cause the best example of course is in sports imagine for example that your favorite baseball team or basketball or football team is playing a game right and you get a new pair of socks and you put on the socks and your your team happens to win right even though the socks have most likely nothing to do with the win our brain thinks there's some sort of causation right my socks cause my team to win because I put on my socks right before the event and this explain Sports superstitions why people eat the same thing before every game why they wear the same thing before every game they think there's some causal event another example might be what you eat for lunch maybe we had some sushi and a couple
2:18 hours later you got sick right you don't feel good now yes of course Sushi could have caus you to be sick but you could have also been getting sick even if you did not eat sushi right it's just time and therefore we think that it is the cause now even though these are kind of fun examples this can actually have real world ramifications one of the most famous examples is the idea that autism is linked to vaccines right if I take a vaccine this is going to lead to autism and the reason this falls under post Hawk FY is because they're typically happen around the same time that kids typically get diagnosed with autism around the same time as vaccines but we know today there is no connection this is a misconception a myth that is generally widespread so correlation does not apply causation all right another reason might be the directionality
3:04 problem yes two things can be related but in which direction let's take a look we know that poor sleep is related to stress right for all of you who've not gotten good sleep you know the next day can be very stressful right so I can say a cause B right and there we go I established causation here's the problem couldn't I also say that if you're stressed that is what caused you to have bad sleep I think I could and that's the idea if I don't know which direction the variables are heading I cannot establish causality take a look at exercise exercising is going to make me happy right it's going to boost my do mean and serotonin levels but could I also argue that happiness if I'm more happy I'm more likely to what I'm more likely to exercise and so if we don't know the
3:50 direction we can only say they are related a link Associated there's some sort of correlation all right another reason we cannot say correlation implies causation is because there might be a third variable also known as the third variable problem or we could say confounding or lurking variable or something unforeseen that connects two things together I said at the beginning that there's a relationship and there is between ice cream sales increasing and shark attacks or drowning right this is a positive correlation and we're like oh my God I should stop eating ice cream but there's always a third variable maybe that is below the surface that connects two things together and instead of A and B we'll they will this as letter C do we know why these two things are related it's because of summer heat waves right let's think about this we
4:38 know that in the summer people eat more ice cream right and we know more people are swimming so there's more shark attacks and drowning and so while it seems like this relationship is there and I'll put a little Mark here there is no relationship it's a spous relationship it is a coincidence or random it's really a third variable that connects them one of my favorite third variable example is cuz I have my own family is the idea that if you eat meals as a family that's correlated to students doing well in school and this is true we know there's a correlation there but it's the idea that if I just go and eat dinner with my family and we have spaghetti all of a sudden my kid's going to do well right but that's not necessarily the case instead there is a third variable right it's not about chicken at the table um that might connect these things together can we
5:24 think about what that is is General parenting style right in other words if you are somebody who believes that we should eat dinner together at the table you probably also better at communicating right with your family members you're probably more likely to talk about schoolwork you're more likely to Advocate and talk about the importance of schoolwork and of course communication is better so yes grades and dinner are good but it's really the style of parenting that is going to connect these together and while these seem related we're going to say there's a third variable all right our last reason why we cannot Savage causation from two things related is because we call confirmation bias my pre-existing beliefs about something my think there's a causation but really two things are just related if man for instance you are
6:11 a doctor or a nurse and it's a Friday night and the hospital is just filled with patience and there chaos everywhere and you look up at the sky and you see the the moon it's a full moon you say of course it's a full moon essentially implying that the reason there's chaos at the hospital is because of the mysteriousness of a full moon right that there's somehow a connection there but all that's really happening is that because you have a pre-existing idea that weird things happen at Full Moon that must be the cause of uh a hospital being chaotic but here's what the doctor should do whenever the hospital is full right with just tons of chaos and tons of people um is look up at the moon and see when it's not a full Moon and what doctors would realize that it's probably equally as full and chaotic when it's a half moon right so this is the idea of confirmation by we only look for things
6:56 to confirm our beliefs and why this is important is we start to establish patterns between things when there is none in Psychology you know what they call this we call this the illus illusory what illusory correlation when we see a relationship between two things when there is none full moons and Chaos vaccines and autism sugar and hyperactivity superstitious beliefs like blue socks and winning there really is nothing there all right so let's do a nice recap of why correlation does not apply causation it could be timing issues post hack FY it could we don't know the relationship or direction of those two variables directionality problem it could be a lurking right an unforeseen variable that we're not aware of or it could be our beliefs Playing Tricks on us right these could be the
7:43 reasons we cannot establish causality all right guys thanks for watching I hope you learned about correlations and causations don't forget to like the video subscribe and at your own risk eat some more ice cream [Music]
