SSIGNTEST procedure

Calculates the sample size for a sign test (R.W. Payne).


Options

PRINT = string
What to print (replication, power); default repl, powe

PROBABILITY = scalar
Significance level at which the response is to be tested; default 0.05

POWER = scalar
The required power (i.e. probability of detection) of the test; default 0.9

TMETHOD = string
Whether to a one- or two-sided test is to be made (onesided, twosided); default twos

REPLICATION = variate
Replication values for which to calculate and print or save the power; default * takes 11 replication values centred around the required number of replicates


Parameters

RESPONSE = scalars
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

NREPLICATES = scalars
Saves the required number of replicates

VREPLICATION = variates
Numbers of replicates for which powers have been calculated

VPOWER = variates
Power (i.e. probability of detection) for the various numbers of replicates


Description

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 NREPLICATES parameter.

   The PRINT option controls printed output, with settings:

    replication
to print the required number of replicates in each sample (i.e. the size of each sample);

    power
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 VREPLICATION and 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.

 

Options: PRINT, PROBABILITY, POWER, TMETHOD, REPLICATION.

Parameters: RESPONSE, NREPLICATES, VREPLICATION, VPOWER.


Method

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.