## Statistics

Association between numerical variables

We can observe if there is a relationship between two numerical variables by using a scatterplot. When observing if a relationship between two variables exist, we observe three main characteristics:

When creating the scatterplot, we usually place the independent (explanatory) variable on the horizontal x-axis and the dependent (response) variable on the vertical y-axis. However, there are some situations where the two variables are dependent on each other, which we refer to as co-dependent. In these situations the variables can be placed on either axis.

**Strength**: how strong is the relationship between the two variables.**Direction**: whether the relationship is increasing or decreasing.**Linearity**: whether the relationship is linear or non-linear.When creating the scatterplot, we usually place the independent (explanatory) variable on the horizontal x-axis and the dependent (response) variable on the vertical y-axis. However, there are some situations where the two variables are dependent on each other, which we refer to as co-dependent. In these situations the variables can be placed on either axis.