Correlation coefficient usually deployed in the space syntax analysis is Pearson’s r, a measure of the strength and direction of the linear relationship between two variables that is defined in terms of the sample covariance and the variables divided by their standard deviation.
Correlation coefficient
Sources
Spiegel, M. (1992) “Correlation Theory.” Ch14 in Theory and Problems of Probability and Statistics, 2nd ed. New York: McGraw-Hill, pp. 294-323.