武乡、沁县及附近几个县的小麦单产存在着周期性波动。采用方差分析分离出七年、五年等五个周期,进而再采用外推法成功地对武乡、沁县1979年、1980年的小麦单产发布了予报,予报1979年为增产,1980年为大幅度减产;并予报1981年的年景仍然不够好。为了证明这一规律确实存在,我们用本方法对1969至1978十年的产量作了推算,并与该十年的历史资料作了对比,拟合率达到90%。 Wheat yields in Wuxiang, Qinxian and nearby counties fluctuated cyclically. An analysis of variance was used to separate out five cycles of seven years and five years, and then the extrapolation method was used to successfully report wheat yields in 1979 and 1980 in Wuxiang and Qinxian. The year was a substantial reduction in production; and it was still not good enough to report the year of 1981. In order to prove that this law does exist, we use this method to estimate the output from 1969 to 1978 and compare it with the historical data of the past decade. The fitting rate is 90%.