Richard Golian

1995-born. Charles University alum. Head of Performance at Mixit. 10+ years in marketing and data.

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Richard Golian

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Correlation vs Causation: What the Difference Really Means

The real difference between correlation and causation, and why confident causal claims worry me
Richard Golian
Richard Golian · 2 763 reads
Hi, I am Richard. On this blog, I share thoughts, personal stories, findings and what I am working on. I hope this article brings you some value.

Today I came across a post on LinkedIn by a digital specialist. He confidently claimed that with an A/B test, we can determine not just correlation, but true causality. He used words like “certainty” as if statistics were part of Newtonian physics, clear, absolute, unquestionable. I am surprised by that level of confidence. I do not have it.

What is the difference between correlation and causation? Correlation means two things move together; causation means one of them actually produces the other. The trouble is that our tools mostly reveal the first while tempting us to claim the second. In years of performance marketing I have watched a team celebrate a campaign because revenue rose the week it launched, when a seasonal spike had lifted everything at once. I have seen an A/B test reported as proof of causality on a sample far too small to rule out chance. Telling correlation from causation is not an academic detail. It is the difference between a decision that genuinely works and one that only looked as though it did.

Correlation vs Causation: Why We See Causes Where There Are None

Our brain craves order. When something happens after something else, we instinctively think: “the first thing caused the second.” Got a headache? Must have been the coffee. We are built to look for causes, even when they are not there, a stubborn cognitive bias.

From an evolutionary perspective, this makes perfect sense. If you hear a rustle in the bushes, it is safer to assume there is a tiger and run, even if it is just the wind. Evolution has taught us it is better to be wrong than dead. Maybe that is why we tend to see patterns in randomness, connections in the unconnected.

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Common questions on this article's topic

Why is the confident use of the word certainty problematic?
Because certainty is far rarer than commonly assumed. In the article, a LinkedIn post by a digital specialist who claimed A/B tests can determine true causality prompts the reflection: statistics operates in probabilities, not absolutes. Even well-designed experiments produce higher probability, not certainty. Confusing statistical significance with proof leads to overconfident decisions based on incomplete understanding.
What is the difference between correlation and causation?
Correlation means two things occur together; causation means one actually produces the other. David Hume argued in the 18th century that we never directly observe causality. We only observe that B follows A repeatedly and assume a causal link. In the article, this philosophical insight is applied to modern marketing and data analysis: statistics can show that two variables are related, but not which one causes the other.
Why does the human brain see causes where there are none?
From an evolutionary perspective, assuming causation was safer than ignoring potential threats. If a rustle in the bushes might be a predator, it is better to run and be wrong than to stay and be dead. In the article, this survival mechanism is identified as the root of a persistent cognitive bias: we instinctively look for causes in random events, see patterns in noise, and construct explanations where none exist.
Can A/B tests prove causation?
A/B tests provide stronger evidence than observational studies because they use randomisation to control for confounding variables. However, they still operate within probability. They increase confidence that a difference is real, but they do not deliver absolute certainty. In the article, the claim that A/B tests determine true causality is challenged: even experiments produce higher probability, not proof in the Newtonian sense.
What does David Hume say about causality?
Hume argued in A Treatise of Human Nature (1739) and An Enquiry Concerning Human Understanding (1748) that we never perceive causation directly. We observe constant conjunction, that B regularly follows A, and our minds create the expectation of a necessary connection. But this connection is a habit of thought, not an observed fact. In the article, this insight is applied to challenge the casual use of the word causality in data-driven fields.
Why does this matter for professionals working with data?
Because overconfident causal claims lead to wrong decisions. In the article, the concern is that professionals in marketing and data analysis use words like certainty and causality as if they were dealing with Newtonian physics, clear, absolute, unquestionable. This false confidence can result in strategies built on correlations mistaken for causes, optimisations based on incomplete understanding, and a culture where questioning assumptions is discouraged.
What are some examples of correlation vs causation?
A classic example: ice cream sales and drowning deaths rise together every summer, yet neither causes the other. A hidden third factor, hot weather, drives both. The article gives a historical version, medieval observers who saw a comet in 1066, then the Battle of Hastings, and blamed the comet for the defeat. A modern version is a team treating an A/B test as proof that a change drove revenue, when a seasonal spike lifted every metric at once. Correlation vs causation matters because the wrong reading turns a coincidence into a confident and costly decision.
Richard Golian

If you have any thoughts, questions, or feedback, feel free to drop me a message at mail@richardgolian.com.

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