html xmlns=”http://www.w3.org/1999/xhtml” xmlns:mml=”http://www.w3.org/1998/Math/MathML” xmlns:epub=”http://www.idpf.org/2007/ops”> 19 Describing the Intervention It might seem easy to define the intervention you want to study, but it rarely is. Although you know what the intervention…
html xmlns=”http://www.w3.org/1999/xhtml” xmlns:mml=”http://www.w3.org/1998/Math/MathML” xmlns:epub=”http://www.idpf.org/2007/ops”> 20 Randomization: What and Why Einstein is often thought to have said that “God does not play dice with the universe.” Without entering either in the…
html xmlns=”http://www.w3.org/1999/xhtml” xmlns:mml=”http://www.w3.org/1998/Math/MathML” xmlns:epub=”http://www.idpf.org/2007/ops”> 16 Study Data: Predictor and Confounding Variables In this chapter we discuss predictor and confounding variables, two categories of variables that are assumed to influence the…
html xmlns=”http://www.w3.org/1999/xhtml” xmlns:mml=”http://www.w3.org/1998/Math/MathML” xmlns:epub=”http://www.idpf.org/2007/ops”> 18 Avoiding Bias This book is about creating a valid study, and a study must be unbiased to be valid, so in some sense this whole…
html xmlns=”http://www.w3.org/1999/xhtml” xmlns:mml=”http://www.w3.org/1998/Math/MathML” xmlns:epub=”http://www.idpf.org/2007/ops”> 15 Study Data: Endpoints In this chapter we discuss the outcome variables, which are the endpoints of a study. These are the most critical measurements in…
html xmlns=”http://www.w3.org/1999/xhtml” xmlns:mml=”http://www.w3.org/1998/Math/MathML” xmlns:epub=”http://www.idpf.org/2007/ops”> 17 Bias Bias is the single biggest potential problem in clinical research. Bias means that the results observed are consistently influenced away from the true result….
html xmlns=”http://www.w3.org/1999/xhtml” xmlns:mml=”http://www.w3.org/1998/Math/MathML” xmlns:epub=”http://www.idpf.org/2007/ops”> 14 Study Data: How Variables Are Used A study is about information. Information is obtained from data. Investigators collect data, examine this data, describe the values…
Figure 13.1. Flow of Participants for Example 13A. Note that although there are about 50 patients attending the clinic, the investigator estimates that only about 5 per month will be…
html xmlns=”http://www.w3.org/1999/xhtml” xmlns:mml=”http://www.w3.org/1998/Math/MathML” xmlns:epub=”http://www.idpf.org/2007/ops”> 12 Study Population A key factor in generalizability is the target population, the people who are the object of the study. In this chapter we discuss…
html xmlns=”http://www.w3.org/1999/xhtml” xmlns:mml=”http://www.w3.org/1998/Math/MathML” xmlns:epub=”http://www.idpf.org/2007/ops”> 11 Generalizability and Validity Generalizability is the ability to draw widely or even universally applicable conclusions from a study. Generalizability is an important goal, because if…
