(Fisherkeller, Friedman and Tukey, 1988)

It is the presence of isolation in conjunction with rotation that gives the system its piecewise linear capability. This is easily demonstrated by considering the simple example of a two-dimensional data set, consisting of two classes whose boundaries are outlined in Figure 3. Clearly, there is no single one-dimensional discriminant direction that can completely separate the two classes (A and B = B1 + B2 + B3)- Applying rotation (both manual and automatic), the user might find a projection that achieves a good partiel separation (such as P, in Figure 3). Using this projection, a mask is constructed at M~1~ and the B~1~ sample is isolated from its complement A + B~1~ + B~3~- These two isolates are then rotated separately, searching for further structure.

(Fisherkeller, Friedman and Tukey, 1988)

Fisherkeller, M. A., Friedman, J. H. and Tukey, J. W. (1988) ‘PRIM-9: An interactive multidimensional data display and analysis system’, Dynamic Graphics for Statistics, pp. 91–109. Available at: [link]

Friendly, M. and Denis, D. (2005) ‘The early origins and development of the scatterplot’, Journal of the History of the Behavioral Sciences. Wiley, 41(2), pp. 103–130. [link]