Proper statistical analysis of data from subchronic and chronic studies is a key aspect of their data analysis and interpretation. We discuss the motivation and illustrate the use of trend tests for continuous quantitative data from such studies. Because responses are often more severe (increase or decrease) with increasing dose, trend tests are the most appropriate statistical procedures to apply. Several parametric and nonparametric trend tests are defined and applied to a small set of male liver weight data from a 14-day rat study. Shortcomings of more standard statistical procedures applied to data from such studies are discussed as well. We recommend the use of trend tests as the customary method for analyzing data from these studies.
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