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.

Email adrian.mander@mrc-bsu.cam.ac.uk

See Also

Related commands:

sampsi (if installed)
samplesize (if installed)   ssc install samplesize (to install this command)
sampsi_reg (if installed)   ssc install sampsi_reg (to install this command)
sampsi_mcc (if installed)   ssc install sampsi_mcc (to install this command)