• Article  

      A remark on consul's (1990) counter-example 

      Sapatinas, Theofanis (1994)
    • Article  

      Short-term load forecasting: The similar shape functional time-series predictor 

      Paparoditis Efstathios, E.; Sapatinas, Theofanis (2013)
      A novel functional time-series methodology for shortterm load forecasting is introduced. The prediction is performed by means of a weighted average of past daily load segments, the shape of which is similar to the expected ...
    • Article  

      Signal detection in underwater sound using wavelets 

      Bailey, T. C.; Powell, K. J.; Krzanowski, W. J.; Sapatinas, Theofanis (1998)
      This article considers the use of wavelet methods in relation to a common signal processing problem, that of detecting transient features in sound recordings that contain interference or distortion. In this particular case, ...
    • Article  

      Some new approaches to infinite divisibility 

      Sapatinas, Theofanis; Shanbhag, D. N.; Gupta, A. K. (2011)
      Using an approach based, amongst other things, on Proposition 1 of Kaluza (1928), Goldie (1967) and, using a different approach based especially on zeros of polynomials, Steutel (1967) have proved that each nondegenerate ...
    • Article  

      Some properties of extreme stable laws and related infinitely divisible random variables 

      Radhakrishna Rao, C.; Shanbhag, D. N.; Sapatinas, Theofanis; Bhaskara Rao, M. (2009)
      In the course of studying the moment sequence { nn : n = 0, 1, ... }, Eaton et al. [1971. On extreme stable laws and some applications. J. Appl. Probab. 8, 794-801] have shown that this sequence, which is, indeed, the ...
    • Article  

      Stochastic expansions in an overcomplete wavelet dictionary 

      Abramovich, F.; Sapatinas, Theofanis; Silverman, B. W. (2000)
      We consider random functions defined in terms of members of an overcomplete wavelet dictionary. The function is modelled as a sum of wavelet components at arbitrary positions and scales where the locations of the wavelet ...
    • Article  

      Testing equality of autocovariance operators for functional time series 

      Pilavakis, Dimitrios; Paparoditis, Efstathios; Sapatinas, Theofanis (2020)
      We consider strictly stationary stochastic processes of Hilbert space-valued random variables and focus on fully functional tests for the equality of the lag-zero autocovariance operators of several independent functional ...
    • Article  

      Testing equality of spectral density operators for functional linear processes 

      Leucht, Anne; Paparoditis, Efstathios; Sapatinas, Theofanis (2018)
      The problem of testing equality of the entire second order structure of two independent functional linear processes is considered. A fully functional L2-type test is developed which evaluates, over all frequencies, the ...
    • Article  

      Testing for additivity and joint effects in multivariate nonparametric regression using Fourier and wavelet methods 

      De Canditiis, D.; Sapatinas, Theofanis (2004)
      We consider the problem of testing for additivity and joint effects in multivariate nonparametric regression when the data are modelled as observations of an unknown response function observed on a d-dimensional (d ≥ 2) ...
    • Article  

      A unified treatment for non-asymptotic and asymptotic approaches to minimax signal detection 

      Marteau, C.; Sapatinas, Theofanis (2015)
      We are concerned with minimax signal detection. In this setting, we discuss non-asymptotic and asymptotic approaches through a unified treatment. In particular, we consider a Gaussian sequence model that contains classical ...
    • Article  

      Wavelet analysis and its statistical applications 

      Abramovich, F.; Bailey, T. C.; Sapatinas, Theofanis (2000)
      In recent years there has been a considerable development in the use of wavelet methods in statistics. As a result, we are now at the stage where it is reasonable to consider such methods to be another standard tool of the ...
    • Article  

      Wavelet density estimation for weighted data 

      Cutillo, L.; De Feis, I.; Nikolaidou, C.; Sapatinas, Theofanis (2014)
      We consider the estimation of a density function on the basis of a random sample from a weighted distribution. We propose linear and nonlinear wavelet density estimators, and provide their asymptotic formulae for mean ...
    • Article  

      Wavelet estimators in nonparametric regression: A comparative simulation study 

      Antoniadis, Anestis; Bigot, J.; Sapatinas, Theofanis (2001)
      Wavelet analysis has been found to be a powerful tool for the nonparametric estimation of spatially-variable objects. We discuss in detail wavelet methods in nonparametric regression, where the data are modelled as ...
    • Article  

      Wavelet instruments for efficiency gains in generalized method of moment models 

      Michis, A.; Sapatinas, Theofanis (2007)
      We propose a simple computational method in the context of generalized method of moments for improving the efficiency of regression coefficient estimates. The gains in efficiency arise by incorporating additional moment ...
    • Article  

      Wavelet methods for continuous-time prediction using Hilbert-valued autoregressive processes 

      Antoniadis, Anestis; Sapatinas, Theofanis (2003)
      We consider the prediction problem of a continuous-time stochastic process on an entire time-interval in terms of its recent past. The approach we adopt is based on the notion of autoregressive Hilbert processes that ...
    • Article  

      Wavelet packet transfer function modelling of nonstationary time series 

      Nason, G. P.; Sapatinas, Theofanis (2002)
      This article shows how a non-decimated wavelet packet transform (NWPT) can be used to model a response time series, Yt in terms of an explanatory time series, Xt. The proposed computational technique transform the explanatory ...
    • Article  

      Wavelet shrinkage for natural exponential families with quadratic variance functions 

      Antoniadis, Anestis; Sapatinas, Theofanis (2001)
      We propose a wavelet shrinkage methodology for univariate natural exponential families with quadratic variance functions, covering the Gaussian, Poisson, gamma, binomial, negative binomial and generalised hyperbolic secant ...
    • Article  

      Wavelet thresholding via a Bayesian approach 

      Abramovich, F.; Sapatinas, Theofanis; Silverman, B. W. (1998)
      We discuss a Bayesian formalism which gives rise to a type of wavelet threshold estimation in nonparametric regression. A prior distribution is imposed on the wavelet coefficients of the unknown response function, designed ...