To calculate the multiple correlation coefficient, Pearson introduced a higher form of mathematics. This played a pivotal role in the professionalization of mathematical statistics as an academic discipline at the end of the 19th century. Pearson learnt this type of mathematics at Cambridge from J.J. Sylvester and Arthur Cayley (1821–95), who had created matrix algebra out of their discovery of the theory of invariants during the mid-19th century.
