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CERNE

Print version ISSN 0104-7760

Abstract

SE, Daniela Cunha da et al. Use of the correlation coefficient between plots in order to improve the accuracy of forest inventories. CERNE [online]. 2013, vol.19, n.4, pp.575-580. ISSN 0104-7760.  https://doi.org/10.1590/S0104-77602013000400007.

Forest inventories are usually compiled without taking into account the existing correlations between sampling units, which is debatable particularly where the calculations involve environmental variables. When the potential correlations between sampling units are overlooked, the accuracy of such inventories becomes distorted in terms of the confidence interval range for the variable of interest, which is volume in cubic meters. The magnitude and form of such distortion will vary according to the correlation intensity between sampling units. This study aimed to present an analysis of the addition of the correlation coefficient to the calculation of the variance of the mean in a systematic sampling procedure of a native forest population or area, as well as its impact on the accuracy of the resulting estimates, with the assumption of independence between sampling units and with the addition of a correlation between sampling units as suggested by Cochran. Results revealed that, where the correlation coefficient was added to the variance of the mean formula, it increased inventory accuracy by about 14.3%, leading to the conclusion that such an effect will occur in any forest inventory being compiled for any forest population or area of interest.

Keywords : Sampling; variance of the mean; native forest.

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