Correlation is not Causation!
Tags: correlation, statistics, causation, discuss
Published: 2023-05-23 10:09:20

```
import numpy as np
import matplotlib.pyplot as plt

# Simulating ice cream sales and sunglasses sales data
np.random.seed(0)
days = 100
temperature = np.random.normal(80, 10, days)  # Simulated temperature data
ice_cream_sales = temperature + np.random.normal(0, 5, days)  # Simulated ice cream sales data
sunglasses_sales = temperature + np.random.normal(0, 8, days)  # Simulated sunglasses sales data

# Calculating correlation coefficient
correlation_coefficient = np.corrcoef(ice_cream_sales, sunglasses_sales)[0, 1]

# Plotting the data
plt.scatter(ice_cream_sales, sunglasses_sales)
plt.xlabel('Ice Cream Sales')
plt.ylabel('Sunglasses Sales')
plt.title(f'Correlation: {correlation_coefficient:.2f}')
plt.show()



![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/er997pzqrny6n9zhvqyz.JPG)
```


The phrase "correlation is not causation" is a fundamental principle in the field of statistics and scientific research. It reminds us that just because two variables are observed to be related or to occur together does not necessarily mean that one variable causes the other to happen.

Correlation refers to a statistical relationship between two or more variables, indicating how they tend to change together. It measures the strength and direction of the relationship, ranging from -1 to 1. A correlation coefficient of 1 indicates a perfect positive correlation, -1 indicates a perfect negative correlation, and 0 indicates no correlation.

Causation, on the other hand, refers to a cause-and-effect relationship between variables, where changes in one variable directly lead to changes in another variable. Establishing causation requires more than just observing a correlation. It involves rigorous experimentation, controlling for other factors, and demonstrating that changes in one variable lead to predictable and consistent changes in another variable.

It's important to be cautious when interpreting correlations because there can be various reasons behind the observed relationship. Correlation does not provide evidence of causation because there might be underlying factors, often called confounding variables, that influence both variables simultaneously. Additionally, the correlation could be coincidental or the result of other factors that were not considered.

To determine causation, researchers often use experimental designs, such as randomized controlled trials, where they manipulate one variable and observe the effect on another variable while controlling for confounding factors. Such experiments allow researchers to make stronger claims about causation.

In summary, while correlations can be useful for identifying relationships between variables, it is crucial to remember that correlation alone does not establish causation. Additional evidence and rigorous research methods are necessary to determine causal relationships between variables.

Let's consider a simple example to illustrate the difference between correlation and causation.

_Example: Ice cream sales and sunglasses sales_

Suppose we observe a strong positive correlation between ice cream sales and sunglasses sales. That is, on hot sunny days, when ice cream sales increase, so do sunglasses sales. Based on this correlation, we might be tempted to conclude that increased ice cream sales cause increased sunglasses sales. However, this would be an example of mistakenly inferring causation from correlation.

Explanation:

1. Correlation: The observed correlation suggests that there is a statistical relationship between ice cream sales and sunglasses sales. It indicates that the two variables tend to change together. On hot sunny days, people are more likely to buy both ice cream and sunglasses.

2. Causation: However, correlation alone does not provide evidence of causation. In this example, ice cream sales and sunglasses sales might be correlated due to a common factor, such as weather. Hot sunny weather could be the driving factor behind both increased ice cream sales and increased sunglasses sales. People are more likely to buy ice cream to cool down and enjoy a refreshing treat, and they also need sunglasses to protect their eyes from the bright sunlight. Thus, weather is a confounding variable that influences both variables simultaneously, creating a correlation between them.

If we were to mistakenly assume causation based on this correlation, we might conclude that selling more ice cream causes an increase in sunglasses sales. However, this conclusion ignores the underlying factor of hot sunny weather, which is the actual cause behind the observed correlation.

To establish causation, we would need to conduct controlled experiments, such as manipulating ice cream sales while controlling for other factors like weather, and observing the effect on sunglasses sales. Only through such rigorous experimentation can we determine whether there is a causal relationship between the variables.

Remembering that correlation does not imply causation is crucial for sound reasoning and accurate interpretation of statistical relationships.