precsize {designsize} R Documentation

## Sample size determination using power and precision analysis

### Description

It determines the ratio between the sample size of power analysis and precision analysis analysis and also, give the required sample sizes.

### Usage

precsize(pR, pT, sigr, sigt, c, alpha, beta)


### Arguments

 pR Incidence rate for the reference group pT Incidence rate for the test group sigr Variability in the reference group sigt Variability in the test group c Constant value for allowance of maximum error margin alpha Level of significance beta The probability of type-II error

### Details

A pre-study power analysis for sample size determination is usually performed to calculate an appropriate sample size for achieving a desired power for detecting a clinically meaningful difference at a prespecified level of significance. In practice, a much larger sample size is expected for detecting a relatively smaller difference, especially for clinical trials with extremely low incidence rate. As a result, sample size determination based on power analysis may not be feasible. So, it is a good suggestion to determine the sample size based on precision analysis.

### Value

precsize returns 3 values:

R

Ratio between the sample size of power analysis and precision analysis

n.power

Sample size required for power analysis

n.precision

Sample size required for precision analysis

### Author(s)

Atanu Bhattacharjee, Rajashree Dey ,Soutik Halder and Akash Pawar

ABdesign crt.match crt.unmatch phsize prsize crsize

### Examples

# The incidence rate of reference group is pR = 0.8 per thousands and that of test group
# is pT = 0.7 per thousands. It is also assumed that  the respective stanadard deviation
# of reference and test group are sigr = 2 and sigt = 1 respectively. The constant value
# is chosen c = 0.08 to allow the  maximum marginal error. The  level of significance is
# alpha = 0.05 and the probability of type-II error is beta = 0.20.

precsize(pR = 0.8, pT = 0.7, sigr = 2, sigt = 1, c = 0.08, alpha = 0.05, beta = 0.20)



[Package designsize version 0.1.0 Index]