a watershed management program is usually based on the results of watershed modeling. accurate modeling results are decided by the appropriate parameters and input data. precipitation is the most important input for watershed modeling. precipitation characteristics usually exhibit significant spatial variation, even within small watersheds. therefore, properly describing the spatial variation o...

To the Editor: I am concerned about errors in simple statistical concepts in articles recently published in Circulation. First, I worry about the widespread use of the standard error of mean (SEM) to describe the variability of numerical data. Specifically, SEM was used in 30% of the clinical investigations and reports and in 76% of the basic science reports analyzed for this purpose (the first...