Variance Modeling in ASReml

Author(s):  
Fikret Isik ◽  
James Holland ◽  
Christian Maltecca
Keyword(s):  
2015 ◽  
Vol 23 (10) ◽  
pp. 1552-1562 ◽  
Author(s):  
Jia-Ching Wang ◽  
Yu-Hao Chin ◽  
Bo-Wei Chen ◽  
Chang-Hong Lin ◽  
Chung-Hsien Wu
Keyword(s):  

2008 ◽  
Vol 19 (08) ◽  
pp. 1221-1242 ◽  
Author(s):  
H. E. ROMAN ◽  
M. PORTO

We discuss a model for simulating a long-time memory in time series characterized in addition by a stochastic variance. The model is based on a combination of fractional Brownian motion (FBM) concepts, for dealing with the long-time memory, with an autoregressive scheme with conditional heteroskedasticity (ARCH), responsible for the stochastic variance of the series, and is denoted as FBMARCH. Unlike well-known fractionally integrated autoregressive models, FBMARCH admits finite second moments. The resulting probability distribution functions have power-law tails with exponents similar to ARCH models. This idea is applied to the description of long-time autocorrelations of absolute returns ubiquitously observed in stock markets.


Author(s):  
Robert J. Bronson ◽  
Hans R. Depold ◽  
Ravi Rajamani ◽  
Somnath Deb ◽  
William H. Morrison ◽  
...  

In this paper we present a systematic data-driven parameter correction and estimation process consisting of outlier detection and removal, relevant input parameter selection, advanced statistical and empirical correlation, and prediction fusion to reduce variance in relevant engine parameter estimates. We model engine parameter deviations from nominal, and show that these methods can result in significant reductions in bias and variance modeling errors. Reducing the error variance increases the signal-to-noise ratio, thereby increasing the reliability and speed of fault-detection algorithms. The overall objective function is to reduce the measurement variances without masking faults. Key parameters modeled include fuel flow, rotor speed(s), and measured temperatures.


2020 ◽  
Vol 10 (2) ◽  
pp. e71-e81 ◽  
Author(s):  
Robert W. Mutter ◽  
Krishan R. Jethwa ◽  
Hok Seum Wan Chan Tseung ◽  
Stephanie M. Wick ◽  
Mohamed M.H. Kahila ◽  
...  

2020 ◽  
Vol 18 (3) ◽  
pp. 532-555
Author(s):  
Fabrizio Cipollini ◽  
Giampiero M Gallo ◽  
Alessandro Palandri

Abstract This article evaluates the in-sample fit and out-of-sample forecasts of various combinations of realized variance models and functions delivering estimates (estimation criteria). Our empirical findings highlight that: independently of the econometrician’s forecasting loss (FL) function, certain estimation criteria perform significantly better than others; the simple ARMA modeling of the log realized variance generates superior forecasts than the Heterogeneous Autoregressive (HAR) family, for any of the FL functions considered; the (2, 1) parameterizations with negative lag-2 coefficient emerge as the benchmark specifications generating the best forecasts and approximating long-range dependence as does the HAR family.


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