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REGRESSION/LS FORMULAS Simplest case. S ( ) = (Y i - )2 dS/d = -2 (Y i - ) Normal equation . A 1 = Y i A = Y-bar S(A) = (Y i - A) 2 = E i 2 Anova identity. Y i 2 = (Y-bar + Y i - Y-bar) 2
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REGRESSION/LS FORMULAS Simplest case. S() = (Yi - )2 dS/d = -2(Yi - ) Normal equation. A 1 = Yi A = Y-bar S(A) = (Yi - A)2 = Ei2 Anova identity. Yi2 = (Y-bar + Yi - Y-bar)2 = (Y-bar2) + (Yi - Y-bar)2 + (Y-bar)(Yi - Y-bar) = nY-bar2 + (Yi - Y-bar)2
Simple regression. (,) = (Yi - - Xi)2 S/ = (-2)(Yi - - Xi) S/ = (-2)(Yi - - Xi)Xi Normal equations. An + B Xi = Yi (1) A Xi + B Xi2 = XiYi (2) A = Y-bar - B X-bar B = (Yi - Y-bar)(Xi - X-bar)/(Xi - X-bar)2 Residuals. Ei = Yi - A - BXi From (1) Ei = 0 From (2) Xi(Yi - A - BXi) = 0 = Xi Ei
Fitted values. Yi-hat = A + B Xi Ei Yi-hat = 0 Anova identity. (Yi - Y-bar)2 = (Yi-hat - Y-bar)2 + (Yi - Yi-hat)2 TSS = RegSS + RSS Yi - Y-bar = Yi-hat - Y-bar + Yi - Yi-hat (Yi-hat - Y-bar)(Yi - Yi-hat) = (Yi-hat - Y-bar)Ei = 0 S(A,B) = Ei2