## The Annals of Mathematical Statistics

### Concerning Compound Randomization in the Binary System

John E. Walsh

#### Abstract

Let us consider a set of approximately random binary digits obtained by some experimental process. This paper outlines a method of compounding the digits of this set to obtain a smaller set of binary digits which is much more nearly random. The method presented has the property that the number of digits in the compounded set is a reasonably large fraction (say of the magnitude $\frac{1}{3}$ or $\frac{1}{4}$) of the original number of digits. If a set of very nearly random decimal digits is required, this can be obtained by first finding a set of very nearly random binary digits and then converting these digits to decimal digits. The concept of "maximum bias" is introduced to measure the degree of randomness of a set of digits. A small maximum bias shows that the set is very nearly random. The question of when a table of approximately random digits can be considered suitable for use as a random digit table is investigated. It is found that a table will be satisfactory for the usual types of situations to which a random digit table is applied if the reciprocal of the number of digits in the table is noticeably greater than the maximum bias of the table.

#### Article information

Source
Ann. Math. Statist., Volume 20, Number 4 (1949), 580-589.

Dates
First available in Project Euclid: 28 April 2007

https://projecteuclid.org/euclid.aoms/1177729950

Digital Object Identifier
doi:10.1214/aoms/1177729950

Mathematical Reviews number (MathSciNet)
MR32156

Zentralblatt MATH identifier
0036.09105

JSTOR