84
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L A W R E N C E E D WA R D S
TABLE 1. Constant-Market-Shares Analysis: Sources of Export Growth, World Regions and Sub-Saharan Africa, 1990–91 to 2005–6 (change as percent of 1990–91 values, in U.S. dollars, except as otherwise specified)
All products 1. Total change 2. Product composition effect 3. Competitiveness effect 4. World growth effect 5. Competitiveness in growing commodities Initial trade value (billions of U.S. dollars)
Manufacturing 6. Total change 7. Product composition effect 8. Competitiveness effect 9. World growth effect 10. Competitiveness in growing commodities Initial trade value (billions of U.S. dollars)
Developing countries
High-income (OECD)
South Africa
Sub-Saharan Africa, excluding South Africa
492 7 283 216 196
155 2 58 216 41
127 30 59 216 38
188 52 24 216 17
404
2,453
24
19
680 12 464 222 325
157 2 63 222 45
300 22 99 222 64
290 61 128 222 95
241
2,138
8
6
Source: Own calculations using UN Comtrade data at the three-digit Standard International Trade Classification (SITC) level and initial period shares as weights. Note: Low-income, middle-income, and developing-country results include Sub-Saharan Africa. The decomposition is calculated as q s0 Q
[ i s0i Qi s0 Q ] i Q1i si,
where q is total exports of the focus country, s is the export share of the focus country, Q is total exports, the subscript i refers to commodity, and the superscripts 0 and 1 refer to initial and final periods. The first term on the righthand side is the world growth effect, the second term is the commodity effect, and the final term is the competitive effect. See Richardson (1971) for some of the shortcomings of this approach.
points) of the improved competitiveness effect for that subgroup has been driven by a restructuring of exports toward rapidly growing products. The results for manufacturing are more positive. The world market share of South Africa and for Sub-Saharan Africa excluding South Africa rose during the period, as reflected in the 290–300 percent increase in export value compared with the 222 percent increase in world trade. Although poor product composition reduced growth, it was more than offset by improvements in competitiveness and by structural shifts toward rapidly growing products (row 10). The trends in Sub-Saharan African trade identified by Ng and Yeats (1996) in the four decades prior to 1990 are thus only partly replicated in the subsequent period. Although exports continue to be concentrated in products with stagnant shares in