Calculates the sample size for a sign test (R.W. Payne).
|What to print (
||Significance level at which the response is to be tested; default 0.05|
||The required power (i.e. probability of detection) of the test; default 0.9|
||Whether to a one- or two-sided test is to be made (
||Replication values for which to calculate and print or save the power; default
||Probability of response (i.e. the probability that an observation in one sample will be greater than the equivalent observation in the other sample) that should be detectable|
||Saves the required number of replicates|
||Numbers of replicates for which powers have been calculated|
||Power (i.e. probability of detection) for the various numbers of replicates|
SSIGNTEST calculates the number of replicates (or sample size) required for a sign test (see procedure
SIGNTEST). By default the calculations are done for a one-sided test (testing for evidence that the location of one sample is greater than the other, but you can set option
TMETHOD=onesided for a two-sided test (testing that locations of the samples are different). The significance level for the test is specified by the
PROBABILITY option (default 0.05 i.e. 5%).
The probability of response (i.e. the probability that an observation in one sample will be greater than the equivalent observation in the other sample) that should be detectable is supplied by the
RESPONSE parameter. The required probability for detection of the response (that is, the power of the test) is specified by the
POWER option (default 0.9). The sample size can be saved using the
||to print the required number of replicates in each sample (i.e. the size of each sample);|
||to print a table giving the power (i.e. probability of detection) provided by a range of numbers of replicates.|
By default both are printed.
The replications and corresponding powers can also be saved, in variates, using the
VPOWER parameters. The
REPLICATION option can specify the replication values for which to calculate and print or save the power; if this is not set, the default is to take 11 replication values centred around the required number of replicates.
An approximate number of replicates is calculated initially assuming a Normal approximation. This is then refined by calculating powers for a range of replications centred around that approximation.
Commands for: Design of experiments.
CAPTION 'SSIGNTEST example',\ !t('One-sided tests, anticipated probabilities of response',\ '0.6, 0.7, 0.8 and 0.9.'); STYLE=meta,plain SSIGNTEST [PRINT=replication,power] 0.6,0.7,0.8,0.9