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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Some nonparametric tests for constancy of regression relationships over time

Roller, William Frederick January 1977 (has links)
Let Y₁, Y₂... be a sequence of random variables obeying the law Y<sub>i</sub> = β’<sub>i</sub> + ε<sub>i</sub>, where β₁, β₂, ... is a sequence of unknown k-dimensional regression vectors; x₁, x₂, ... is a sequence of known k-dimensional regressor vectors; and ε₁ , ε₂, ... is a sequence of independent and identically distributed random variables. Assume that β₁ = ... = β<sub>m</sub> = β, m ≥ k, and that β̂₀ is an asymptotically normal estimate of β based on Y₁ , ..., Y<sub>m</sub>. This study develops nonparametric procedures for testing H₀: = β = β<sub>m+1</sub> = β<sub>m+2</sub> = …. The proposed tests involve sequences of truncated sequential tests. That is, a function of the residuals Y<sub>m+1</sub> - β̂’₀ x<sub>m+1</sub>, …, Y<sub>m+N</sub> - β̂’₀ x<sub>m+N</sub> is examined for a shift in the model. If no shift is indicated all m+N observations are pooled and a new estimate of β, β̂₁, is formed. The next N residuals are then examined for a shift. The procedure continues until a.shift is indicated. Brownian motion results are used to obtain approximate critical values when the function of the residuals is: the cumulative sum of the signs of the residuals; the sequential Wilcoxon scores; the ordinary cumulative sums of residuals. Exact results are obtained for the cumulative sum of signs procedure when testing for a shift in median. Asymptotic relative efficiency results are also obtained. / Ph. D.

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