Geostatistical Modeling in Presence of Extreme Values

  • Author / Creator
    Babakhani, Mahshid
  • Geostatistical modeling in presence of extreme values needs special attention. Certain extreme high values known as outliers require proper treatment or mineral resources may be overstated. A number of methodologies are proposed in this thesis to identify and manage outliers. The main goal of the outlier management strategies is to keep the outliers but control their influence on local block estimates, if required, by reducing their values. The variogram is an essential geostatistical tool that is highly sensitive to outlier high values. There are alternatives to the experimental traditional variogram. The pairwise relative variogram is known to be a very robust alternative to the experimental traditional variogram in presence of outlier high values. There are two issues with the pairwise relative variogram; (1) an unknown sill, and (2) its convergence to the wrong variogram. Solutions to both of these problems are developed and documented in this thesis. Another contribution of this thesis is a simulation-based approach for cutting outlier values. The volume of influence of an outlier is identified. The uncertainty in the mean of the volume of influence is established by simulation. Then, the outlier value is reduced until the estimated quantity of metal within the identified volume is reasonable relative to the distribution coming from simulation. The outlier management strategies presented in this thesis will provide practical assistance for geological modeling for engineering evaluations.

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  • Graduation date
  • Type of Item
  • Degree
    Master of Science
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    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.