👉 In mathematics, a correlation is an association between two variables that can be mathematically expressed as a linear relationship. If there exists a positive correlation between two variables X and Y, then as one variable increases, the other variable tends to increase at approximately the same rate. Conversely, if there exists a negative correlation, then as one variable increases, the other variable tends to decrease at approximately the same rate. For example, in the case of temperature and humidity, the relationship between these two variables is