The sequence of positive random variables {
Yt} is called a stationary lognormal process with parameters μ, σ
2 and ρ
h,
h=0, ±1, ±2, …, if the sequence of logarithmic variables {
ln Yt} is stationary and Gaussian with mean μ, variance σ
2 and autocorrelation coefficients ρ
h. This paper deals with the problem of estimating the autocorrelation coefficients of a stationary lognormal process with known μ and σ
2. Efficiency of the usual sample autocorrelations relative to a simplified estimate is studied under the assumption that the transformed process is Markovian. The result leads to the choice of the biased simplified estimate as a better estimate than the unbiased sample autocorrelations for small lag
h and small σ. Other unbiased estimates are constructed and their variances are evaluated.
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