Reliability and Survival Methods • Recurrence Analysis • Recurrence Analysis Platform Options • Fit Model
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Fit Model
The Fit Model option is used to fit models for the Recurrence Intensity and Cumulative functions. There are four models available for describing the intensity and cumulative functions. You can fit the models with constant parameters, or with parameters that are functions of effects.
Select Fit Model from the platform red-triangle menu to produce the Recurrence Model Specification window shown in Recurrence Model Specification.
Recurrence Model Specification
You can select one of four models, with the following Intensity and Cumulative functions:
Power Nonhomogeneous Poisson Process
I(t) =
C(t) =
Proportional Intensity Poisson Process
I(t) =
C(t) =
Loglinear Nonhomogeneous Poisson Process
I(t) =
C(t) = =
Homogeneous Poisson Process
I(t) =
C(t) =
where t is the age of the product.
Scale and Shape Parameters defines each model parameter as a scale parameter or a shape parameter.
Scale and Shape Parameters 
Model
Scale Parameter
Shape Parameter
Power NHPP
θ
β
Proportional Intensity PP
γ
δ
Loglinear NHPP
γ
δ
Homogeneous PP
γ
none
Note the following:
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For the Recurrence Model Specification window (Recurrence Model Specification), if you include Scale Effects or Shape Effects, the scale and shape parameters in Scale and Shape Parameters are modeled as functions of the effects. To fit the models with constant scale and shape parameters, do not include any Scale Effects or Shape Effects.
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The Homogeneous Poisson Process is a special case compared to the other models. The Power NHPP and the Proportional Intensity Poisson Process are equivalent for one-term models, but the Proportional Intensity model seems to fit more reliably for complex models.
Click Run Model to fit the model and see the model report (Model Report).
Model Report
The report has the following options on the red triangle menu:
Profiler
Launches the Profiler showing the Intensity and Cumulative functions.
Effect Marginals
Evaluates the parameter functions for each level of the categorical effect, holding other effects at neutral values. This helps you see how different the parameter functions are between groups. This is available only when you specify categorical effects.
Test Homogeneity
Tests if the process is homogeneous. This option is not available for the Homogeneous Poisson Process model.
Effect Likelihood Ratio Test
Produces a test for each effect in the model. This option is available only if there are effects in the model.
Specific Intensity and Cumulative
Computes the intensity and cumulative values associated with particular time and effect values. The confidence intervals are profile likelihood intervals.
Specific Time for Cumulative
Computes the time associated with a particular number of recurrences and effect values.
Save Intensity Formula
Saves the Intensity formula to the data table.
Save Cumulative Formula
Saves the Cumulative formula to the data table.
Remove Fit
Removes the model report.

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Help created on 9/19/2017