Correlation vs Causation Statistics Example 4

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Example 4

hard
A pharmaceutical company observes that patients who take their new supplement have lower rates of heart disease compared to those who don't. The company wants to claim the supplement prevents heart disease. What type of study would provide the strongest evidence, and what conditions must it satisfy?

Solution

  1. 1
    Step 1: A randomised controlled trial (RCT) provides the strongest evidence for causation. Participants must be randomly assigned to either the supplement group or a placebo control group.
  2. 2
    Step 2: Key conditions: (a) random assignment to eliminate confounding variables, (b) blinding (double-blind ideally) so neither participants nor researchers know who gets the supplement, (c) sufficiently large sample size for statistical power, (d) control for other variables that affect heart disease.

Answer

A double-blind randomised controlled trial with random assignment, a placebo control group, blinding, and adequate sample size would provide the strongest evidence for causation.
Establishing causation in medicine requires randomised controlled trials because they control for confounding variables through random assignment. Without randomisation, any observed difference could be due to pre-existing differences between the groups rather than the treatment itself.

About Correlation vs Causation

Correlation shows that two variables move together in some pattern; causation means one variable actually makes the other change. Observing a correlation does not prove causation because a hidden third variable (confounder) may be driving both.

Learn more about Correlation vs Causation →

More Correlation vs Causation Examples

Example 1 easy

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Example 2 medium

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Example 3 medium

Data shows that countries with higher chocolate consumption per capita have more Nobel Prize winners

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