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Task 10. Sample Adequacy (cont.) <br />If adequate sample size is not met for a particular parameter <br />in a particular vegetation type, sampling will stop at the maximum sample <br />size prescribed by CPiLR personnel, that is 50 in affected areas and 30 <br />in reference areas. <br />Task 11. Comparability Testing <br />Following collection and analysis of data the comparability of <br />reference areas and analogous affected areas will be evaluated statistically <br />for cover and production with the formula: <br />XA XC <br />t= <br />s- - <br />n n XA - xC <br />where sxA - xC = s2 An+n C <br />p A C / <br />and s2 =\nA-1/ sA + `nC-1/ sC <br />p nA-11 + !nC-l~ <br />where xA = affected area mean <br />xC = control area mean <br />t = two-tailed t-value <br />sA = variance among affected area samples <br />s~ = variance among control area samples <br />nA = number of affected area samples <br />nC = number control area samples <br />The above calculated t value is compared to a two-tailed t value <br />at 95R confidence with appropriate degrees of freedom, as presented in a <br />table. If the calculated value is less, the "comparability" of the <br />reference and affected area is deemed acceptable. <br />Task 12. Data Analysis <br />Vegetation production samples will be dried and weighed in our <br />laboratory as the field program advances. Likewise, cover and woody <br />plant density data xill be analyzed as the study progresses. All data <br />will be summarized in tabular form and presented and discussed in the report. <br />-4- <br />