public ThreeParamItemInformationFunction(ThreeParamModelParameters modelParameters)
{
_alpha = modelParameters.Alpha;
_chi = modelParameters.Chi;
_probabilityFunction = new ThreeParamProbabilityFunction(modelParameters);
}
public ThreeParamItemInformationFunction(ThreeParamModelParameters modelParameters)
{
_alpha = modelParameters.Alpha;
_chi = modelParameters.Chi;
_probabilityFunction = new ThreeParamProbabilityFunction(modelParameters);
}
public FourParamItemInformationFunction(FourParamModelParameters modelParameters)
{
_alpha = modelParameters.Alpha;
_chi = modelParameters.Chi;
_epsilon = modelParameters.Epsilon;
_probabilityFunction = new FourParamProbabilityFunction(modelParameters);
}
/// <summary>
/// Adds the given element to the collection
/// </summary>
/// <param name="item">The item to add</param>
public override void Add(IModelElement item)
{
if ((this._parent.Function_ProbabilityFunctionLiteral == null))
{
IProbabilityFunction function_ProbabilityFunctionLiteralCasted = item.As <IProbabilityFunction>();
if ((function_ProbabilityFunctionLiteralCasted != null))
{
this._parent.Function_ProbabilityFunctionLiteral = function_ProbabilityFunctionLiteralCasted;
return;
}
}
}
// The standard error of estimate (SEE) for the location parameter theta. The general formula is given by (2.11) on page 28.
public double Calculate(List <QuestionInfo> questionHistory, double theta)
{
List <IModelParameters> modelParametersList = questionHistory.Select(x => x.Question.ModelParameters).ToList();
List <int> responseVector = questionHistory.Select(x => (int)x.Score).ToList();
double sum = 0;
for (int i = 0; i < responseVector.Count; i++)
{
IModelParameters modelParameters = modelParametersList[i];
IProbabilityFunction probabilityFunction = _probabilityFunctionFactory.Build(modelParameters);
double p = probabilityFunction.ProbabilityOfCorrectResponse(theta);
double pPrime = probabilityFunction.FirstThetaDerivative(theta);
sum += pPrime * pPrime / (p * (1 - p));
}
return(1 / Math.Sqrt(sum));
}
public TwoParamItemInformationFunction(TwoParamModelParameters modelParameters)
{
_alpha = modelParameters.Alpha;
_twoParamProbabilityFunction = new TwoParamProbabilityFunction(modelParameters);
}
public TwoParamItemInformationFunction(TwoParamModelParameters modelParameters)
{
_alpha = modelParameters.Alpha;
_twoParamProbabilityFunction = new TwoParamProbabilityFunction(modelParameters);
}
