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OB-31-05 DY:32AN FROM-~I6 GRAND JUICTION FIELD OFFICE <br /> <br />Satterthwaites' Approximation <br />B70 241 1516 <br />T-T27 P.004/OD5 F-035 <br />Conservatively assume that reference area and bond release area variances are unequal. As <br />such, Sotterthwaites' Approximation is used to determine the appropriate degrees of <br />freedom for use in the two sample nest (in this case a `reverse null" t-test will be <br />employed, to demonstrate that the reclaimetl area mean exceeds the standard 18096 of the <br />reference area meant. <br />In addition, the proper stantlard error term Ithe tlenominator in the t-test statistic) must be <br />calculated. When using the Satterthw@ite Approximation, the term Is the Satterthwaite <br />Standard Error. <br />In Stap 7 below, the Satterthwahe Standard Error is calculated. In Step 2, the <br />Satterthwaite degrees of freedom is calculated, using the Standard Error value calculated in <br />Step 1. In Step 3, the reverse null, two sample t-test is run, using the Standard Ercor and <br />degrees of freedom calculated in Steps 1 and 2. <br />Step 1, Satterthwake Standard Errar <br />z <br />"s S`''t s'S~ ~' ~ ~` Sn f~ <br />,_____ t <br />n br /1 y.ef <br />f.'~re''` i <br />~saf`= s~~fl,cxa.{c Sfan-lrw~C~rur' <br />_ aq, a <br />br '' 3~,~,(~sfreq.52»t.~e Ve•-;a7~ <br />/t b~ ~ $~•,:A Q eJ`+-r6R. A/`~ sw"~° ~e di7-e <br />~,~ti_~iryelt ~'ac <br />Step 2, Sattenhwalta Derpees of Fresdom <br />d~~t _ s~~t <br />Y <br />-safe r• f ( a9~SF~hF <br />j..-~ <br />nAr f ~rcl''~ <br />w~~~ <br />7Z~i ~?S~o <br />Z~ ~ 9 J <br />~B <br />~s [go,Y 3~ <br />.r--r -r- <br />~a _aa <br />