I. INTRODUCTION: Observations are taken in the laboratory and from these observations certain conclusions are drawn. Since no observation or series of observations is absolutely accurate, it is often desirable to check the dependability of the conclusions by a study of the errors in the experiment.
Suppose that an experiment on the relation between the pressure and volume of a gas is performed in the laboratory and that the conclusion is the statement of the law that the volume is inversely proportional to the pressure. The experiment does not prove that the law is absolutely accurate but only that within certain limits, determined by the accuracy of the experiment, it has been found to be true. Small departures from the law will always be found and it should be possible to determine whether these departures indicate that the law is not exactly true or whether they are due to unavoidable experimental errors. Even if in this experiment no significant departures were found, observations with more refined apparatus might show conclusively that the law was only an approximation to the truth.
