INTRODUCTION

It is proposed in this chapter to give a short account of some of the special points worth noting in connection with the fundamental business of carrying out basic statistical calculations, with regard to both the arithmetical aspects and the equipment required. There are many important details which can be easily overlooked by those who are mainly concerned in dealing with the more elementary work themselves, and who do not need to become involved in the niceties of advanced computation. Unless calculations are sufficiently accurate it is obvious that the statistical tests and analyses based on them may be completely vitiated. Nevertheless, one wants to avoid laborious complexities as far as possible. We shall therefore consider below some of the most important features to which special attention should be given, in particular, avoiding mistakes, achieving sufficient numerical accuracy, exhibiting the precision of statistical results, and choosing the most suitable level of automatic assistance, whether this be a simple or advanced pocket calculator, or a computer with specialised statistical software.

HOW TO AVOID MISTAKES

Before going on to look at computational details, we shall first consider some aspects of the general question of obtaining accurate calculations. It is very easy, even for those who are experienced in numerical work, to make small slips in reading or writing figures on a worksheet, in transferring numbers to or from a desk calculating machine or pocket calculator, in attaching plus and minus signs, or in interpreting brackets in algebraic formulae, etc.