Dr.N. Balakrishna
http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2103
2016-07-23T09:16:23ZProduct autoregressive models for non-negative variables
http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/4725
Product autoregressive models for non-negative variables
Balakrishna, N; Abraham, B
When variables in time series context are non-negative, such as for volatility, survival
time or wave heights, a multiplicative autoregressive model of the type Xt = Xα
t−1Vt ,
0 ≤ α < 1, t = 1, 2, . . . may give the preferred dependent structure. In this paper,
we study the properties of such models and propose methods for parameter estimation.
Explicit solutions of the model are obtained in the case of gamma marginal distribution
Statistics and Probability Letters 82 (2012) 1530–1537
2012-05-07T00:00:00ZThreshold Autoregressive Model for a Time Series Data
http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2858
Threshold Autoregressive Model for a Time Series Data
Kesavan Nampoothiri,C; Balakrishna, N
In this paper we try to fit a threshold autoregressive (TAR) model to time series data of monthly coconut oil prices at Cochin market. The procedure proposed by Tsay [7] for fitting the TAR model is briefly presented. The fitted model is compared with a simple autoregressive (AR) model. The results are in favour of TAR process. Thus the monthly coconut oil prices exhibit a type of non-linearity which can be accounted for by a threshold model.
2000-01-01T00:00:00ZNonparametric Estimation of the Average Availability
http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2857
Nonparametric Estimation of the Average Availability
Balakrishna, N; Angel, Mathew
The average availability of a repairable system is the expected proportion of time that the system is operating in the interval [0, t]. The present article discusses the nonparametric estimation of the average availability when (i) the data on 'n' complete cycles of system operation are available, (ii) the data are subject to right censorship, and (iii) the process is observed upto a specified time 'T'. In each case, a nonparametric confidence interval for the average availability is also constructed. Simulations are conducted to assess the performance of the estimators.
2009-01-01T00:00:00ZComputationally Efficient Bootstrap Prediction Intervals for Returns and Volatilities in ARCH and GARCH Processes
http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2856
Computationally Efficient Bootstrap Prediction Intervals for Returns and Volatilities in ARCH and GARCH Processes
Chen, Bei; Gel, Yulia R; Balakrishna, N; Abraham, Bovas
We propose a novel, simple, efficient and distribution-free re-sampling technique for developing prediction intervals for returns and volatilities following ARCH/GARCH models. In particular, our key idea is to employ a Box–Jenkins linear representation of an ARCH/GARCH equation and then to adapt a sieve bootstrap procedure to the nonlinear GARCH framework. Our simulation studies indicate that the new re-sampling method provides sharp and well calibrated prediction intervals for both returns and volatilities while reducing computational costs by up to 100 times, compared to other available re-sampling techniques for ARCH/GARCH models. The proposed procedure is illustrated by an application to Yen/U.S. dollar daily exchange rate data.
2011-01-01T00:00:00Z