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对小麦、大麦、燕麦、玉米和水稻在本世纪内的产量进行了产量－时间回归分析。对玉米、水稻只在全国水平上进行了分析（因为它们的主栽区较集中）；对小麦、大麦和燕麦则在全国水平之外，还于新南威尔士（ＮＳＷ）州，维多利亚（Ｖｉｃ）州，南澳（ＳＡ）、西澳（ＷＡ）和昆士兰（Ｏｌｄ）州分别进行了这种分析。所采用的回归函数可以表明农艺改良对产量的影响，并且残差可以代表这类影响之外的产量变异。此外还测定了一项代表稳产性的残差值，即实际产量可占的比例（相对残差）。不同作物的产量差异很大，但作物之间变异系数和平均产量间无相关性。正如所料，５种作物近些年的产量（或称当前产量）均比本世纪早期的产量高。将每种作物的残差和相对残差对应于年份划成小区。小麦产量的残差在本世纪内既无提高也无降低，但其相对残差表明其稳产性是明显趋于提高的。大麦和燕麦的趋势与小麦相近。玉米产量的残差随着时间的推移而增大，但其相对残差保持未变。水稻产量的残差最大，但没有随时间而提高或降低的趋势；以产量比例测定的稳产性则有明显的提高。３种冬性谷类作物在各州的产量趋势进一步证实了在全国水平上获得的这些结果。总之不论哪种作物，栽培于现代管理条件下的新品种均比早期种植的老品种?
Yield-time regression analyzes of wheat, barley, oats, maize and rice production during the century were conducted. For maize, rice is only analyzed at the national level (because of their more concentrated areas); at the national level for wheat, barley and oats, in New South Wales, Vic, State, South Australia (SA), Western Australia (WA) and Old State of Queensland. The regression function used can indicate the effect of agronomic improvement on yield, and the residuals can represent yield variability beyond this impact. In addition, a residual value representing the stability of production, ie, the proportion of actual output (relative residuals), was determined. The yield of different crops varies greatly, but there is no correlation between the coefficient of variation and the average yield of crops. As expected, the output of five crops in recent years, or current output, is higher than in the early part of the century. The residuals and relative residuals for each crop are plotted as years against the plot. The residuals of wheat yields have neither increased nor decreased over the century, but their relative residuals indicate that their productivity is clearly on the rise. The trend of barley and oats is similar to that of wheat. The residuals of corn production increase with time, but their relative residuals remain unchanged. Rice had the largest residual yield, but did not increase or decrease over time; yield stability was significantly improved as measured by yield. The trend in yield of the three types of winter cereal crops in each state further confirms these results at the national level. In short, no matter what kind of crops, cultivated under modern management conditions than the new varieties of early cultivation of old varieties?