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"1r: Mike Savage • • <br />' Colorado Mined Land Reclamation Division <br />May 23, 1983 <br />Page 2 <br />A z statistic is [hen calculated to estimate the actual number <br />of standard deviations of the difference between .9 pr and pm. <br />z = .9 pr - pm (derived from Arkin <br /> 1 + 1 and Colton, 1970; and <br /> pq Mendenhall, 1975) <br /> n n <br /> r m <br />where z = [he number of standard deviations of the difference <br /> between p and p2 <br />I <br />P n <br />= p <br />+ mn <br /> r <br />r <br />m <br /> nl + n2 <br />n = total number of cover transects on the reference areas <br />r <br />n = total number of cover transects on the re vegetated area <br />m <br />If the value calculated for z exceeds 1.283, the null hypothesis will be rejected <br />and it will be concluded that the re vegetated site failed to meet the standard. <br />Obviously if the value from the re vegetated site (p2) ) 90Y, of the value from <br />the reference area (pl) success is indicated without the need for hypothesis <br />testing. <br />The described testing procedure is based on the normal approximation. This is <br />an appropriate assumption when the sample size (number of transects) >5 and the <br />absolute value of r 1 ~ L 99 _ ~~p <br />~ nJ V p Y q <br />is less than 0.3 (Box, et. al., 1978). We have evaluated Trapper's cover data for <br />1980-1982 and determined that this criteria is satisfied. <br />The herbaceous plant production data would be similarly evaluated by hypothesis <br />testing at a 90Y statistical confidence level as follows: <br />110: X 1 .9 X <br />m r <br />Ra: 7i G .9 X <br />m r <br />where x = the average production from the revege[ated area <br />m <br />x = the average production from the reference areas <br />r <br />the z statistic is then calculated from: <br />.9X - x <br />r m <br />z = <br />sr + s m <br />n n <br />r m <br />