ABSTRACT
In correlation, the degree to which two variables vary together is measured. Correlation is, therefore, a measure of the strength of the relationship between two variables. Regression is used to calculate the line of best fit through the data, in order to establish or estimate the dependence of one variable upon the other and/or enable predictions of one variable to be made from knowledge of another. The measured variable is the dependent variable, because its value depends on the value of the controlled, or independent, variable. When illustrating a correlation, the same logic is used for deciding which variable should be on the x and y axes. Autocorrelation is a particular problem with climatic variables where wetter days tend to be warmer, have greater cloud cover and fewer sunshine hours. The cells contain the Pearson product moment correlation coefficients for each pair of variables.
