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help for ^sampicc^
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^Sample Size and Power Estimation for Single ICC^
---------------------------------------------------
.^sampicc ^ [, ^A^lpha(#) ^P^ower(#) ^S^ample(#) ^W^idth(#) ^CI^ ]
^Description^
^-----------^
^sampicc^ computes the sample size or, alternatively, the power required to test an
ICC (p1) against a null value (p0). In addition, the program will compute the sample
size for a specified width of a confidence interval for the ICC. There are two forms
of the command:
^FORM 1^: To compute the sample size for a test of a hypothesized value against a null
^------^ value, three inputs are required:
^p1^ --- the hypothesized ICC
^p0^ --- the null value for ICC
^reps^ --- the number of replicates taken on each subject (must be an integer)
^Options for Form 1^
^------------------^
^alpha(#)^ The Type 1 error value (default is 5%)
^power(#)^ The power for the test (default is 80%)
^sample(#)^ The number of subjects to be tested. If specified, the program computes
power for the given sample size
^Syntax for Form 1^
^-----------------^
.^sampicc ^,
^NOTE to Form 1^: To be conservative, all sample size estimates are rounded to the next highest
integer value, if the solution involves a decimal (e.g., 15.1 resolves to 16)
^FORM 2^: To compute the sample size for a specified width or, alternatively, to compute the width
^------^ of a confidence interval for a given sample size, the ^ci^ option must be specified.
^p1^ --- the hypothesized ICC
^reps^ --- the number of replicates taken on each subject (must be an integer)
^Options for Form 2^
^------------------^
^ci^ ci ^is required^ for estimations relating to confidence intervals
^alpha(#)^ In this form, alpha(#) refers to 100(1-alpha)% CI level. The default
alpha is .05 (i.e., 95% CI)
^sample(#)^ The number of subjects to be tested.
^width(#)^ The desired width of the confidence interval. This value must be between
0 and 1
^Syntax for Form 2^
^-----------------^
. ^sampicc p1 reps, w(#) ci^
. ^sampicc p1 reps, s(#) ci^
^Examples^
^--------^
To compute sample size for an ICC against a null value, assuming a critical level of
5% and power of 80% (Form 1)
.^sampicc .4 .1 3^
To compute power, for an ICC against a null, with the sample size given (Form 1)
. ^sampicc .6 .1 3, s(15)^
To compute sample size for a specified width of the confidence interval (Form 2)
. ^sampicc .5 2, w(.15) ci^
To estimate width of a 90% CI for a given sample size (Form 2)
. ^sampicc .5 2, s(100) alpha(.10) ci^
______________________________________________________________________________________________
^References^
^----------^
Shoukri MM, Asyali MH, Donner A. Sample size requirements for the design of reliability study:
review and new results. Statistical Methods in Medical Research, 2004; 13: 251-271.
Walter SD, Eliasziw M, & Donner A. Sample size and optimal designs for reliability studies,
Statistics in Medicine, 1998; 17: 101-110.
Author
------
Paul F. Visintainer, PhD
Springfield, MA 01089
visint46@gmail.com
Also see
--------
Manual or on-line help for: @sampsi@, @sxd3_1@ for sskdlg on SSC.