134 Statistical Discussion Forum

References

Moore, L.M. (1988). Singular factorial designs resulting from missing pairs of designs points. J. Statist.

Plann. Inference 19, 325-340.

Subir Ghosh

Department of Statistics University of California Riverside, CA 92521

F20. An enveloping regression procedure

Given N bivariate observations (xi, yi) (i = 1,2, . . . , N) with x1 5 x2 5 x3 5 ... 5 x,,

we consider the following basic enveloping regression procedure. Choose an integer

k where 3 I k I N and run a standard regression program for each of the N-k+ 1 sets

wherer=1,2,..., N- k + 1. This will provide N- k + 1 straight lines and these might

appear to envelope a fairly definite curve. This curve can be regarded as a regression

curve which might often be of value in exploratory data analysis. The optimal choice

of k will certainly not be the same on all occasions, and the interpretation will often

be somewhat subjective.

This proposal could be compared with the use of moving averages.

I.J. Good

F21. Chaotics vs. Chaology

The mathematical theory of chaos has emerged as a fairly new branch of statistics

or physics, and the subject merits a name. The two natural contenders are Chaofogy and Chaotics of which M.V. Berry of the University of Bristol prefers the former

and I prefer the latter. He gives two arguments favoring chaology.

(i) Chaofogy is already a word in that it occurs in the complete Oxford English Dictionary and refers to an old branch of theology.

(ii) The pair (chaos, chaology) is analogous to (cosmos, cosmology) and (thana-

tos, thanatology).

My replies are

(i) A new subject merits a new name.

Statistical Discussion Forum 135

(ii) Chaotic is a familiar word but cosmetic and thanatotic are not words, at

least they are not in the OED. Note too that mechanikos led to mechanics and

statikos led to statistics.

(iii) & (iv) A few colleagues and I find chaotics more euphonic and more self-

explanatory (especially when spoken) than chaology. The latter sounds like the

study of someone named Kay.

I would be interested to receive the opinion of anyone who cares enough to write.

I.J. Good