Chung Chin explains that she used data for 1991 because it made calculations relatively simple. In 1991 the PRC was strongly encouraging foreign firms to go all out to export goods and earn foreign exchange, and Taiwan firms were given little access to the domestic market. Therefore using total Taiwanese investment in the economic formula to calculate the contribution made to mainland Chinese exports would give a close approximation to the actual figure.
「以一九九一年做基準比較單純」，鍾琴解釋，那時大陸還全力鼓勵外商「出口創匯」，大部分台商沒什麼內銷可做，因此將投資金額套用經濟學上的公式，換算出口移轉效果，誤差不會太大。