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ZTestPowerAnalysis Class |
Power analysis for one-sample Z-Tests.
Inheritance HierarchySystemObject
Accord.Statistics.Testing.PowerBaseOneSamplePowerAnalysis
Accord.Statistics.Testing.PowerZTestPowerAnalysis
Accord.Statistics.Testing.PowerBaseOneSamplePowerAnalysis
Accord.Statistics.Testing.PowerZTestPowerAnalysis
Namespace: Accord.Statistics.Testing.Power
Assembly: Accord.Statistics (in Accord.Statistics.dll) Version: 3.8.0
SyntaxThe ZTestPowerAnalysis type exposes the following members.
Constructors| Name | Description | |
|---|---|---|
 | ZTestPowerAnalysis(OneSampleHypothesis) |
Creates a new ZTestPowerAnalysis.
|
| ZTestPowerAnalysis(TwoSampleZTest) |
Creates a new ZTestPowerAnalysis.
|
Properties| Name | Description | |
|---|---|---|
 | Effect |
Gets or sets the effect size of the test.
(Inherited from BaseOneSamplePowerAnalysis.) |
| Power |
Gets or sets the power of the test, also
known as the (1-Beta error rate).
(Inherited from BaseOneSamplePowerAnalysis.) |
| Samples |
Gets or sets the number of samples
considered in the test.
(Inherited from BaseOneSamplePowerAnalysis.) |
| Size |
Gets or sets the significance level
for the test. Also known as alpha.
(Inherited from BaseOneSamplePowerAnalysis.) |
| Tail |
Gets the test type.
(Inherited from BaseOneSamplePowerAnalysis.) |
Methods| Name | Description | |
|---|---|---|
| Clone |
Creates a new object that is a copy of the current instance.
(Inherited from BaseOneSamplePowerAnalysis.) |
| ComputeEffect |
Computes the minimum detectable effect size for the test
considering the power given in Power, the
number of samples in Samples and the significance
level Size.
(Overrides BaseOneSamplePowerAnalysisComputeEffect.) |
| ComputePower | (Overrides BaseOneSamplePowerAnalysisComputePower.) |
| ComputeSamples |
Gets the recommended sample size for the test to attain
the power indicating in Power considering
values of Effect and Size.
(Overrides BaseOneSamplePowerAnalysisComputeSamples.) |
| Equals | Determines whether the specified object is equal to the current object. (Inherited from Object.) |
 | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
| GetDiferentiableUnits |
Gets the minimum difference in the experiment units
to which it is possible to detect a difference.
(Inherited from BaseOneSamplePowerAnalysis.) |
 | GetEffectSize |
Estimates the number of samples necessary to attain the
required power level for the given effect size.
|
| GetHashCode | Serves as the default hash function. (Inherited from Object.) |
| GetSampleSize |
Estimates the number of samples necessary to attain the
required power level for the given effect size.
|
| GetType | Gets the Type of the current instance. (Inherited from Object.) |
| MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
| ToString |
Converts the numeric power of this test to its equivalent string representation.
(Inherited from BaseOneSamplePowerAnalysis.) |
| ToString(String, IFormatProvider) |
Converts the numeric power of this test to its equivalent string representation.
(Inherited from BaseOneSamplePowerAnalysis.) |
Extension Methods| Name | Description | |
|---|---|---|
 | HasMethod |
Checks whether an object implements a method with the given name.
(Defined by ExtensionMethods.) |
| IsEqual |
Compares two objects for equality, performing an elementwise
comparison if the elements are vectors or matrices.
(Defined by Matrix.) |
| To(Type) | Overloaded.
Converts an object into another type, irrespective of whether
the conversion can be done at compile time or not. This can be
used to convert generic types to numeric types during runtime.
(Defined by ExtensionMethods.) |
| ToT | Overloaded.
Converts an object into another type, irrespective of whether
the conversion can be done at compile time or not. This can be
used to convert generic types to numeric types during runtime.
(Defined by ExtensionMethods.) |
Examples
// When creating a power analysis, we have three things we can
// change. We can always freely configure two of those things
// and then ask the analysis to give us the third.
var analysis = new ZTestPowerAnalysis(OneSampleHypothesis.ValueIsDifferentFromHypothesis);
// Those are:
double e = analysis.Effect; // the test's minimum detectable effect size
double n = analysis.Samples; // the number of samples in the test
double p = analysis.Power; // the probability of committing a type-2 error
// Let's set the desired effect size and the
// number of samples so we can get the power
analysis.Effect = 0.2; // we would like to detect at least 0.2 std. dev. apart
analysis.Samples = 60; // we would like to use at most 60 samples
analysis.ComputePower(); // what will be the power of this test?
double power = analysis.Power; // The power is going to be 0.34 (or 34%)
// Let's set the desired power and the number
// of samples so we can get the effect size
analysis.Power = 0.8; // we would like to create a test with 80% power
analysis.Samples = 60; // we would like to use at most 60 samples
analysis.ComputeEffect(); // what would be the minimum effect size we can detect?
double effect = analysis.Effect; // The effect will be 0.36 standard deviations.
// Let's set the desired power and the effect
// size so we can get the number of samples
analysis.Power = 0.8; // we would like to create a test with 80% power
analysis.Effect = 0.2; // we would like to detect at least 0.2 std. dev. apart
analysis.ComputeSamples();
double samples = analysis.Samples; // We would need around 197 samples.
See Also