Choosing the proper sample size for an investigation is one of the crucial jobs required of a statistician. Regardless of whether the statistician is deciding the number of patients to select in a ...

Power analyses and sample size calculations are important parts of many research projects. Often, before data are even collected, it is necessary to calculate and justify the required sample size for ...

Define statistical power List the potential consequences of doing a study that has low power, and also a study that has too much power. Explain what a type 1 and type ...

Read the sections on power and sample size (pages 37-39 and page 85) in Carl Schwarz's notes, Chapter 6. Some basic ideas: The significance level of a test protects against incorrect rejection of the ...

Background: In this article, we discuss the purpose of sample size calculation in clinical trials, the need for it, and the methods by which it is accomplished. Study samples that are either too small ...

The probability that the null hypothesis will be rejected when it is actually true is called the false positive rate and is determined by the significance level of the test (called alpha which is ...

1. Röhrig B, du Prel JB, Blettner M: Study design in medical research – Part 2 of a series on evaluation of scientific publications [Studiendesign in der medizinischen Forschung. Teil 2 der Serie zur ...