The UK pig market series
The original pig market series are given as five columns in the file PigsUnadj.txt The series following adjustment for small fixed quarterly patterns are in the file PigsAdj.txt. This adjustment was carried out by least squares fitting of constant and trend terms plus three fixed quarterly cycles. However, only the cycles were subtracted out from the series. The five columns correspond, in order, to the measures of New breeding animals, Numbers to market, Profitability, Breeding herd reduction and Breeding herd size. However, the numbers were formed in various ways, the first being an index, and for the analyses in the book the series were scaled by the respective factors of 10, 100, 1, 1000, 10 to make them comparable in magnitude.
The series are quarterly records over the twelve year period from 1967 to 1978, and were supplied by the then UK Ministry of Agriculture, Fisheries and Foods. The data quality is variable, for example the New breeding animals were determined from a June census supplemented with sample surveys at three other quarters. The picture is of Gloucester Old Spot piglets.