Effect of Size-Biased Sampling on Resource Predictions from the Three-Part Method for Quantitative Mineral Resource Assessment—A Case Study of the Gold Mines in the Timmins-Kirkland Lake Area of the Abitibi Greenstone Belt, Canada

Scientific Investigations Report 2018-5149
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Abstract

The three-part method for quantitative mineral resource assessment is used by the U.S. Geological Survey to predict, within a specified assessment area, the number of undiscovered mineral deposits and the quantity of mineral resources in those undiscovered deposits. The effects of size-biased sampling on such predictions are evaluated in a case study that involves gold mines from the Timmins-Kirkland Lake area of the Abitibi greenstone belt, Canada. The gold mines are divided, based upon the time of the assessment, into two groups: existing mines and future mines. The total produced gold for the existing mines are used to predict, with the three-part method, the total produced gold for the future mines. Then the predictions are compared to the known, total produced gold for the future mines. For comparisons using the mean, the predictions are 1.6 to 12 times too high, depending upon the time of the assessment and the probability density function characterizing the total produced gold in the existing mines. For comparisons using the median, the predictions are 1.3 to 10 times too high, depending upon the time of the assessment. The reason for these excessively high predictions is that the three-part method is based on the assumption that the total produced gold from the existing mines is representative of the total produced gold in the future mines; this assumption is inappropriate because of size-biased sampling. There is reason to be concerned that size-biased sampling adversely affected the resource predictions of previous U.S. Geological Survey assessments that were conducted with the three-part method.

Suggested Citation

Ellefsen, K.J., 2019, Effect of size-biased sampling on resource predictions from the three-part method for quantita-tive mineral resource assessment—A case study of the gold mines in the Timmins-Kirkland Lake area of the Abitibi greenstone belt, Canada: U.S. Geological Scientific Investigations Report 2018–5149, 15 p., https://doi.org/10.3133/sir20185149.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Background
  • Three-Part Method
  • Evaluation of Predictions from the Three-Part Method
  • Discussion
  • Future Research
  • Software and Reproducibility
  • References Cited
  • Appendix 1. Data Compilation
  • Appendix 2. Sample Space
  • Appendix 3. Requirements for Datasets

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Effect of size-biased sampling on resource predictions from the three-part method for quantitative mineral resource assessment—A case study of the gold mines in the Timmins-Kirkland Lake area of the Abitibi greenstone belt, Canada:
Series title Scientific Investigations Report
Series number 2018-5149
DOI 10.3133/sir20185149
Year Published 2019
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Geology, Geophysics, and Geochemistry Science Center
Description Report: v, 15 p.; Companion File
Country Canada
Other Geospatial Ontario Province, Quebec Province
Online Only (Y/N) Y