.- help for ^sampicc^ .- ^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.