There are three main types of mechanical switches: clicky, linear, and tactile. Here are examples and sound tests of a variety of each kind. Clicky Vs Tactile Vs Linear Mechanical Keyboard Switches ...

D. R. Cox, Nanny Wermuth, Tests of Linearity, Multivariate Normality and the Adequacy of Linear Scores, Journal of the Royal Statistical Society. Series C (Applied Statistics), Vol. 43, No. 2 (1994), ...