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TTestPowerAnalysis Class

Power analysis for one-sample T-Tests.
Inheritance Hierarchy
SystemObject
  Accord.Statistics.Testing.PowerBaseOneSamplePowerAnalysis
    Accord.Statistics.Testing.PowerTTestPowerAnalysis

Namespace:  Accord.Statistics.Testing.Power
Assembly:  Accord.Statistics (in Accord.Statistics.dll) Version: 3.6.0
Syntax
[SerializableAttribute]
public class TTestPowerAnalysis : BaseOneSamplePowerAnalysis
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The TTestPowerAnalysis type exposes the following members.

Constructors
  NameDescription
Public methodTTestPowerAnalysis(OneSampleHypothesis)
Creates a new TTestPowerAnalysis.
Public methodTTestPowerAnalysis(TwoSampleTTest)
Creates a new TTestPowerAnalysis.
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Properties
  NameDescription
Public propertyEffect
Gets or sets the effect size of the test.
(Inherited from BaseOneSamplePowerAnalysis.)
Public propertyPower
Gets or sets the power of the test, also known as the (1-Beta error rate).
(Inherited from BaseOneSamplePowerAnalysis.)
Public propertySamples
Gets or sets the number of samples considered in the test.
(Inherited from BaseOneSamplePowerAnalysis.)
Public propertySize
Gets or sets the significance level for the test. Also known as alpha.
(Inherited from BaseOneSamplePowerAnalysis.)
Public propertyTail
Gets the test type.
(Inherited from BaseOneSamplePowerAnalysis.)
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Methods
  NameDescription
Public methodClone
Creates a new object that is a copy of the current instance.
(Inherited from BaseOneSamplePowerAnalysis.)
Public methodComputeEffect
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.
(Inherited from BaseOneSamplePowerAnalysis.)
Public methodComputePower
Computes the power for a test with givens values of effect size and number of samples under Size.
(Overrides BaseOneSamplePowerAnalysisComputePower.)
Public methodComputeSamples
Computes recommended sample size for the test to attain the power indicated in Power considering values of Effect and Size.
(Inherited from BaseOneSamplePowerAnalysis.)
Public methodEquals
Determines whether the specified object is equal to the current object.
(Inherited from Object.)
Protected methodFinalize
Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.
(Inherited from Object.)
Public methodGetDiferentiableUnits
Gets the minimum difference in the experiment units to which it is possible to detect a difference.
(Inherited from BaseOneSamplePowerAnalysis.)
Public methodStatic memberGetEffectSize
Estimates the number of samples necessary to attain the required power level for the given effect size.
Public methodGetHashCode
Serves as the default hash function.
(Inherited from Object.)
Public methodStatic memberGetSampleSize
Estimates the number of samples necessary to attain the required power level for the given effect size.
Public methodGetType
Gets the Type of the current instance.
(Inherited from Object.)
Protected methodMemberwiseClone
Creates a shallow copy of the current Object.
(Inherited from Object.)
Public methodToString
Converts the numeric power of this test to its equivalent string representation.
(Inherited from BaseOneSamplePowerAnalysis.)
Public methodToString(String, IFormatProvider)
Converts the numeric power of this test to its equivalent string representation.
(Inherited from BaseOneSamplePowerAnalysis.)
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Extension Methods
  NameDescription
Public Extension MethodHasMethod
Checks whether an object implements a method with the given name.
(Defined by ExtensionMethods.)
Public Extension MethodIsEqual
Compares two objects for equality, performing an elementwise comparison if the elements are vectors or matrices.
(Defined by Matrix.)
Public Extension MethodToT
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.)
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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 TTestPowerAnalysis(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 0.33 (or 33%)

// 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 199 samples.
See Also