This feature requires IBM® SPSS® Statistics Base
Edition.
Power analysis plays a pivotal role in a study plan, design, and conduction.
The calculation of power is usually before any sample data have been collected, except possibly from
a small pilot study. The precise estimation of the power may tell investigators how likely it is
that a statistically significant difference will be detected based on a finite sample size under a
true alternative hypothesis. If the power is too low, there is little chance of detecting a
significant difference, and nonsignificant results are likely even if real differences truly
exist.
Binomial distribution is based on a sequence of Bernoulli trials. It can be used to model
experiments, including a fixed number of total trials, which are assumed to be independent of each
other. Each trial leads to a dichotomous result, with the same probability for a successful
outcome.
The relatedsample binomial estimates the power of McNemar's test to compare
two proportion parameters based on the matched pair subjects sampled from two related binomial
populations.
 From the menus choose:
 Select a test assumption Estimate setting
(Sample size or Power).

When Sample size is selected, enter either a
Single power value for sample size estimation value (the value must be a
single value between 0 and 1), or select Grid power values and then click
Grid to view projected sample sizes for a range of specific Power values.
For more information, see Power Analysis: Grid Values.
 When Power is selected as the test assumption
Estimate method, enter the appropriate Total number of
pairs value.
 Select to specify testing values for either proportions or
counts.
 You can optionally select Test values are marginal to
control whether or not the specified proportions or counts values are marginal. When Test
values are marginal is enabled, you must specify a Correlation between
matched pairs value. The value must be a single value between 1 and 1.
 Select a method for estimating the power.
 Normal approximation
 Enables normal approximation. This is the default setting.
 Binomial enumeration
 Enables the binomial enumeration method. Optionally, use the Time
limit field to specify the maximum number of minutes allowed to estimate the sample
size. When the time limit is reached, the analysis is terminated and a warning message is displayed.
When specified, the value must be a single positive integer to denote the number of minutes. The
default setting is 5 minutes.
 Select whether the test is one or twosided.
 Nondirectional (twosided) analysis
 When selected, a twosided test is used. This is the default setting.
 Directional (onesided) analysis
 When selected, power is computed for a onesided test.
 Optionally, specify the significance level of the Type I error rate for the
test in the Significance level field. The value must be a single double value
between 0 and 1. The default value is 0.05.
 Optionally, click Plot to specify Power Analysis of RelatedSample Binomial Test settings (chart output, twodimensional plot settings, and
threedimensional plot settings).
Note: Plot is available only when Power is selected as the
test assumption Estimate and Binomial enumeration is
not selected.
 Optionally, click Precision to estimate the sample
size based on confidence intervals by specifying the values of the confidence interval halfwidths.
For more information, see Power Analysis: Precision.
Note: Precision is available only when
Sample size is selected as the test assumption
Estimate method and Nondirectional (twosided)
analysis is selected as the Test Direction.
This procedure pastes POWER PROPORTIONS RELATED
command syntax.