Kawagoe, Hayami and Ruttan (1985) (

Kawagoe, Hayami and Ruttan (1985) (hereinafter K-H-R) and Hayami
and Ruttan (1985), following up on Hayami and Ruttan (1970), estimated an
agricultural production function using intercountry data for three years -
1960, 1970 and 1980. However, in fact, the flow variables, such as output and
fertilizer input, are averages of (1957-62), (1967-72) and (1975-80) respectively,
whereas the stock variables, such as land, are the actual levels at 1960,
1970 and 1980 respectively. Outputs (y) are measured as gross outputs net of
agricultural intermediate products such as feed and seeds and expressed in
terms of wheat-equivalents or wheat units. Five conventional inputs, labor
(Xi), land (X,), livestock (X,), fertilizer (X,), and machinery (X,), and two
non-conventional inputs, general and technical education (X, and X,), are
distinguished.