雜草科學研究上經常使用劑量－反應分析。在除草劑之劑量－反應分析上已廣泛使用log-logistic模式。此模式具有在生物上有意義的參數並且可藉由一些統計軟體容易地求解。本篇報告對於log-logistic模式的理論做介紹並且使用一組實際的資料來解釋log-logistic模式。將嘉磷塞(glyphosate)稀釋不同倍數，然後施用於玉米種子以及香附子塊根上，實驗進行三天調查其發芽率。使用SAS與SigmaPlot軟體作統計分析，結果除草劑嘉磷塞對於玉米種子與香附子塊根的作用位置是相同的，此外此二軟體分析結果十分相似。

Dose-response analysis is usually employed in the weed science study. Log-logistic model has been adopted widely in herbicide dose-response analysis. This model has biologistically meaningful parameters and can be easily solved by some statistical packages. In this paper the log-logistic model was reviewed in theory and a real data set was used to explain the log-logistic model. Glyphosate was diluted and applied in corn seed and purple nutsedage tuber. The germination rate was investigated within three days. Both SAS and SigmaPlot packages were used in analysis. It was found that the herbicide glyphosate was acting at the same site of action in corn seed and purple nutsedge tuber and two statistical packages achieved a similar result.