ABSTRACT
The term 'run' suggests something taking place over time. Runs of index numbers are indeed almost always temporal comparisons, the case considered here. The analysis applies, however, to spatial or inter-group comparisons with only minor modifications. Take a run of index numbers at annual intervals, prices or quantities in a current year t being compared with those in some reference-base year 0. When the run is given more frequently, e.g. monthly or quarterly, the additional problem of seasonal variations arises and this is considered later (4.8). The index can in general run backwards as well as forwards and the current year is to be written: t =. . . - 2, - 1, 0, 1, 2, . . . . In a special but quite usual case, the run commences with the base year and comparisons are forward from year 0 to year t where t =0, 1, 2, ....
