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Using a z table the actual confidence limit obtained can then be <br />determined, 85.1. <br />Equality between control and affected area aegetation mover and <br />~~ production was testers by the following formula (Larson, 1980) <br />X. - X. <br />t = ~ 1 <br />_ e <br />Z / n~ + nl <br />p njni <br />s (I\ J <br />where: <br />t = calculated t value <br />e <br />xj = mean vegetation cover or production (control area) <br />xi = mean vegetation Dover or production (affected area) <br />nj = sample size (control) <br />ni = sample size (affected) <br />2 mj + mi <br />sp = nJ + nl _2 <br />where: <br />mj = (n-1) s2 (control) <br />mi = (n-1) s2 (affected) <br />2 <br />s = variance <br />The null hypothesis states that there is no difference between control <br />area and affected area vegetation cover (or production). If the <br />calculated t valt~ (te) is less than or equal to the tabled t value at <br />the 95g confidence level (t95), then the null hypothesis is accepted. <br />It is rejected when to is greater than t95' <br /> <br />-19- <br />