# Correlation and Heatmaps

This lesson will introduce how to calculate and visualize correlations between quantities in python.

## We'll cover the following

## Correlation

**Correlation** is a mathematical technique that shows how strongly two variables are linked. It quantifies the strength of the relationship. For instance, we know that the weight and height of a person are correlated. Taller people tend to have more weight. Hence, we say that height and weight are correlated.

Correlation is measured in terms of a number called **correlation coefficient**, which ranges from $-1$ to $1$. The value of $1$ or $-1$ denotes complete correlation, while $0$ indicates that no correlation is present between the two variables. Negative values mean there is an inverse relationship between the two variables, while a positive value denotes a direct relationship.

Pandas has the function `corr`

that can be called on a dataframe. Let’s see an example of this on our Default of Credit Card Clients Dataset.

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