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Showing 2 results for Kamranfar
Rahim Chinipardaz, Hoda Kamranfar,
Volume 3, Issue 1 (9-2009)
Abstract
This paper is concerned with the study of the effect of outliers in GARCH models. Four common outliers are considered: additive outliers, innovation outliers, level change and temporary change. Each of the outlier is embedded to a GARCH model and then the effectness of outliers in this model is studied. The residuals of the models have been investigated for both cases, the usual GARCH model and the GARCH model in the present of outliers.
Hoda Kamranfar, Javad Etminan, Majid Chahkandi,
Volume 14, Issue 2 (2-2021)
Abstract
A repairable system with two types of failures is studied. Type I failure (minor failure) is removed by a minimal repair, whereas type II failure (catastrophic failure) is modified by an unplanned replacement. The first failure of the system follows a Weibull probability distribution and two maintenance policies are considered. In the first policy, the system is replaced at time T or the first type II failure, and in the second policy, the system is replaced at the nth type I failure, the first type II failure or at time T, whichever takes place first. This paper aims to derive a general representation for the likelihood function of the proposed models. The likelihood-ratio test statistic, maximum likelihood estimators and asymptotic confidence intervals for the parameters are also found. Finally, a Monte Carlo simulation is conducted to illustrate the results.
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