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Statistical Methods <br />• <br />STATISTICAL DESIGN <br />Cover and herbaceous production data were collected in all areas. Woody plant density data <br />were collected in the 2003 and 2005 Reclaimed Areas, but were not collected in any of the <br />reference areas. Sampling followed a single stage statistical design. <br />Sample locations in reclaimed areas were randomly selected using an internal script routine <br />within ArcGIS 9.2 software. Minimum spacing between the random sample points was 170 feet <br />(one 50 m transect length). The SCC-assigned number of samples for a given parameter in a <br />given area reflected previously experienced sample variability or the level of precision required for <br />that area. <br />In the extended reference areas, each reference unit was gridded and numbered. Grid cell size <br />was 200 feet X 200 feet. These grid cells were placed contiguously by hand on maps of 1:4,800 <br />scale. Sample locations were selected as the center points of grid cells selected using random <br />numbers generated by computer. <br />Sample points were located in the field using Garmin III GPS units and topographic maps. Cover <br />• and woody plant density transects were located and oriented using a blind throw of a meter stick. <br />The final location of each herbaceous production plot was chosen with a blind throw of the <br />sampling hoop made from the origin of the associated cover/woody plant density transect. At <br />each cover/woody plant density sampling location, the slope (percent) and aspect of the site were <br />determined and recorded, as was the orientation of the transect (in degrees not corrected for <br />magnetic declination). <br />SAMPLE ADEQUACY CALCULATIONS <br />Sample adequacy calculations for parameter estimation without hypothesis testing were carried <br />out using the formula as prescribed by the Colorado Mined Land Reclamation Board for <br />parameter estimation without hypothesis testing (CDMG 1995): <br />t2s2 <br />mm- _ <br />(d x )z <br />where: <br />to =one-tailed t-value with (n-1) degrees of freedom, a=0.10 <br />4 <br />