```
help sampsi_rho
-------------------------------------------------------------------------------

Title

Calculates Sample Size or Power for Pearson Correlation

Syntax

sampsi_rho [, options]

options               Description
-------------------------------------------------------------------------
Main
null(#)              specifies the null value of the Pearson
correlation, the default is 0.
alt(#)               specifies the alternative value of the
correlation, the default is 0.5.
n1(#)                specifies the sample size, the default is 100.
alpha(#)             specifies the significance level, the default is
0.05.
power(#)             specifies the power, the default is 0.9.
solve()              specifies whether to calculate the sample size or
the power, the default is n.
onesided             specifies whether the alternative hypothesis is
onesided, the default is a two-sided test.
-------------------------------------------------------------------------

Description

sampsi_rho calculates either the sample size or power for a Pearson
correlation. The formula for sample size is ((Za+Zb)/(delta))^2 + 3 where
delta is the difference between test value and the null value, Za is the
signficance Z-value and Zb is the power Z-value. The correlations are
transformed using the Fisher z transformation 1/2ln((1+rho)/(1-rho)) this
z is normally distributed with a standard deviation of 1/sqrt(N-3).

Options

+------+
----+ Main +-------------------------------------------------------------

null(#) specifies the null value of the Pearson correlation, the default
is 0.

alt(#) specifies the alternative value of the correlation, the default is
0.5.

n1(#) specifies the sample size, the default is 100.

alpha(#) specifies the significance level, the default is 0.05.

power(#) specifies the power, the default is 0.9.

solve() specifies whether to calculate the sample size or the power, the
default is n.

onesided specifies whether the alternative hypothesis is onesided, the
default is a two-sided test.

Examples

sampsi_rho

sampsi_rho, solve(power)

sampsi_rho, solve(power) n(10) alt(0.2)

sampsi_rho, p(0.8) onesided

Author

Adrian Mander, MRC Biostatistics Unit, Cambridge, UK.