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<br /> <br />If the difference between the means exceeded the calculated critical value, <br />then means were significantly different at the stated confidence level. <br />The previous tale listed the mean, standard deviation and sample number <br />for each of the data sets. The following table lists the comparison being <br />made, difference between means, tabular t-values, critical values (from the <br />formula) and whether or not the null hypothesis was accepted or rejected. <br />Aspen <br />Biomass <br />Cover <br />Woody Plant Density <br />Trees <br />Shrubs <br />Sagebrush <br />Biomass <br />Cover <br />Woody Plant Density <br />Gambel Oak <br />Biomass <br />Cover <br />Woody Plant Density <br />Trees <br />Shrubs <br />Chokecherry <br />Biomass <br />Cover <br />Woody Plant Density <br />t-TEST COMPARISONS <br />X1 - X2 t(.05, nl + n2-2) <br />Critical Null 1 <br />Value Hypothesis <br />9.1 1.701 20.6 R <br />4.4 2.015 5.8 R <br />20.5 2.015 9.6 A2 <br />23.0 1.860 21.2 A2 <br />20.0 1.717 17.7 A <br />3.0 - ~ 1.943 9.6 R <br />20.5 ~ 1.943 21.8 R <br />8.5 1.701 9. 4 R <br />19.7 1.943 6.8 A <br />3.8 1.943 10.6 R <br />5.5 1.943 37.1 R <br />0.8 1.701 12.6 R <br />7.7 2.015 6.7 A <br />26.3 2.015 24.6 A <br />`R = reject null hypothesis <br />A = accept null hypothesis <br />tin these cases the measured reference area woody plant density was significantly <br />less than on the mine area. <br />• <br />