Combining indicator patterns in weights of evidence modeling for resource evaluation

Abstract

The weights of evidence model for combining indicator patterns in mineral resource evaluation is briefly explained with emphasis on the effect of undiscovered deposits on the estimation of the weights and posterior probabilities. A group of six statistical tests is proposed for analyzing the interaction of t w o or three indicator patterns with the point pattern for mineral deposits. A distinction is made between statistics that depend on choice of unit cell size and those that are approximately or completely independent of it. Finally, weights of evidence are compared to regression coefficients obtained by means of the logistic model.

Modelling Deforestation and Land Cover Transitions of Tropical Peatlands in Sumatra, Indonesia Using Remote Sensed Land Cover Data Sets

“…Dinamica has been shown to be a suitable modeling tool for land cover change in a comparison study of alternative land change modeling tools in a binary, forest/non-forest, study in peat swamp forest areas of Kalimantan [26]. Dinamica is a weights-of-evidence model, a method that traditionally is used in geological applications [27][28][29][30][31]. Weights-of-evidence is based upon a series of factors, evidential themes, which must be conditionally independent of each other for each land cover transition identified [32].…”

Fractal pattern integration for mineral potential estimation

“…Buffer zones in figure 4B and binary aero-magnetic patterns in figure 4C were delineated and optimized in terms of the contrast C = W + -W-(cf. Agterberg, 1989Agterberg, , 1992, respectively. Gold anomalies in figure 4D were delineated by statistical and fractal methods (Cheng, 1995;others, 1994d, 1995).…”

“…These and other GIS capabilities have led to the development of new methods for statistical and nonstatistical pattern integration, simulating the practice by exploration geologists of superimposing maps for delineating favorable areas. For instance, the weights of evidence method was proposed and has been intensively used for data integration (Agterberg, 1989(Agterberg, , 1992Agterberg and others, 1993b;BonhamCarter 1994;Bonham-Carter and others, 1988;Cheng and others, 1994a). This method can be implemented by means of GIS on the basis of a polygon overlay map, called the unique conditions map, where each polygon represents a unique combination of the classes of input maps, although the calculations of the weights are performed by defining a fundamental unit area, or "unit cell."…”

Sediment Ecosystem Assessment Protocol (SEAP): An Accurate and Integrated Weight-of-Evidence Based System

“…Model fit was evaluated by computing the proportion of low-quality and high-quality sites (raw data) successfully predicted by the analysis (discussed and illustrated in the next section). Further description of WLR can be found in Agterberg (1992) and Raines et al (2002). Advantages of this approach are the adjustment of probability computations to incorporate the study area extent (area) represented by each unique combination of stressors, as well as a lack of assumption of conditional independence of explanatory variables in the prediction of relative probabilities of the biological response.…”

“…A spatial association (studentized contrast) value of 1.95 (absolute value) represents approximately 95% confidence for a significant spatial association (Robinson et al, 2004). For an additional description of WOE, see Agterberg (1992), Robinson et al (2004) andBonham Carter (1994). Environmental variables were identified as potential stressors when the spatial association of low-quality sites (25th centile) were significantly different (magnitude of ~[1.95]) than that of higher quality sites for a particular level(s) of the environmental variable (ex.…”