P-values: What they are and what they are not, will look in detail at good examples of using p-values and how to interpret them. After reviewing widely understood problems with p-values, attention is drawn to regularly encountered use of p-values where it is less clear what their correct interpretation actually is. Furthermore, we demonstrate why… Read More
The positive and negative predictive values of a dignostic test depend not only on its sensitivity and specificity, but also the prevalence of the disease (or the pre-test probability of disease). This interactive display illustrates that inter-dependence. Move the sensitivity, specificity, and disease prevalence sliders, and watch the positive and negative predictive value sliders change… Read More
If you’re an avid SAS user, you’re likely very familiar with SAS macros. SAS macros are a key component to creating efficient and concise code. Although you cannot use macros in R, R offers other features like functions and loops that can perform the same tasks as SAS macros. Using apply() to loop over variables… Read More
This is a short comparison of SAS and R code in the context of generating multiple datasets. In this example, the mpg dataset from R is used to show how one might use a SAS Macro to subset the data by car class, followed by the R equivalent. You will see that in SAS, the macro… Read More
Researchers at the University of Tennessee Health Science Center (UTHSC) and the Memphis Veterans Affairs (VA) Medical Center were part of the SPRINT MIND (Systolic Blood Pressure Intervention Trial Memory and Cognition IN Decreased Hypertension) multisite clinical trial, which released study findings today showing that intensive lowering of blood pressure reduced the risk of… Read More
