Thesis (Ph.D.)-Unversity of Natal, 1994.Estimates of the value of manufacturing sector output enter into many economic indices, especially those measuring productivity. The South African Central Statistical Services has twice made substantial errors in the output series. Revisions to correct the first of these raised the growth rate in manufacturing over the period 1970-80 from 2,6 per cent per annum (compound) to 5 per cent. This episode is not common knowledge. After examining the conceptual difficulties involved in producing output stimates, a practical technique for detecting errors in the series , the Euler Consistency Test, is presented. Developed, refined, and then applied to the South African data, it predicted, retrospectively, the first set of errors (using only the information available at the time those errors were made), then detected another set of errors , not previously known to exist. The study records the process by which the CSS was made to concede this second error. Acknowledgement only came after protracted correspondence and an examination conducted by a special committee formed to investigate my complaints. With 1979 set equal to 100, the output level in 1988 was originally given as 113,8. After investigation, the CSS raised this to 126,1. The magnitude of this second error is equivalent to the omission of the total output of the two SASOL plants commissioned during the early 1980s. Estimates of productivity growth by the National Productivity Institute using these incorrect figures are shown to have created a misleading picture of the sector's performance, especially in the sensitive debate over the relationship between wage and productivity growth. An attempt is made to lay the groundwork of an analytical framework for comprehending (from a Marxist point of view) the activities of ideological state apparatusses like the NPI. A review of the literature on theory choice is conducted, and the necessarily political nature of this activity is explored. The relative impotence of I science' in the face of ideology in a conflict-ridden society is considered. The question of the significance of disagreements between economists is examined, and prospects for convergence and consensus on certain issues are weighed