correlation coefficient

A correlation coefficient is a number between -1 and 1 that shows us how two things are related. A positive correlation coefficient (between 0 and 1) means that when one thing increases, the other increases too. For example, if people's height increases, their weight also increases - this is a positive correlation.

A negative correlation coefficient (between 0 and -1) means that when one thing increases, the other decreases. For example, if the price of something increases, the amount of people buying it decreases - this is a negative correlation.

When the correlation coefficient is close to 0, it means that the two things aren't really related.