“…The sources of the differential patterns of change between the regions in the number of livestock units can be examined further using the technique of shift and share analysis, (Higgins, 1978;Bowler, 1981), which allows for the disaggregation of the total change in the number of livestock units in each region into three components: (a) anational component giving the change that would have occurred if the aggregates for all livestock categories in each region changed at the same rate, assuming the area of land devoted to livestock Enterprise substitution in Irish Agriculture Table 9: Localisation coefficients by region for major fanning enterprises, 1970,1980 and 1989 remained unchanged, (b) a structural component reflecting the change due to the mix of livestock categories in the region and the trends in each category in relation to overall national trends, and (c) a competitive component giving the change that can be attributed to specific regional factors which result in deviations from the overall trend for each livestock category. These components are usually referred to as the Regional share (R), the Proportional shift (P) and the Differential shift (R) respectively.…”