Comparison between sampling methods

N. Ríos, V. Acosta, C. Gaillard de Benítez, M. Pece

Abstract


This research was carried out in a giant Chinaberry tree (Melia azedarach var. gigantea) plantation located in the Province of Santiago del Estero, Argentina. At seven years of age, the plantation had reached the stage of high forest, with an original spacing of 4 m X 4 m. Fixed area plots are already installed for a study on growth and yield. Measurements were conducted on these plots by using two sampling methods of probability proportional to size (PPS), i.e., horizontal point sampling and horizontal line sampling, with variable size plots. Basal area factors K=1 and K=2 of the Bitterlich relascope were used in order to select the trees which made up the sample. Basal area, volume, and number of trees per hectare were estimated for each method. The resulting data were assorted by diameter class and subjected to analysis of variance in a random block design, where diameter classes were considered as blocks, basal area factors, as treatments, and fixed area plot sampling methods as controls. The relative efficiency of each method was also calculated. No significant difference among treatments was found at the one percent probability level. The horizontal point and the horizontal line sampling estimates are as accurate as those obtained with the control, whereas the relative efficiency of the PPS methods was greater than that of the control.

Keywords


Sampling; Comparison of Sampling Methods; Horizontal Point Sampling; Horizontal Line Sampling





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