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Quantitative Methods Using more than one explanatory variable
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Why use more than one? Intervening or “3rd” variables (schoolchildren’s maths) Reducing error variation (saplings) There is more than one interesting predictor (trees)
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Using more than one explanatory variable Statistical elimination
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Using more than one explanatory variable Statistical elimination
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Using more than one explanatory variable Statistical elimination
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Using more than one explanatory variable Statistical elimination
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Using more than one explanatory variable Statistical elimination
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Using more than one explanatory variable Sequential and Adjusted Sums of Squares
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Using more than one explanatory variable Sequential and Adjusted Sums of Squares
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Using more than one explanatory variable Sequential and Adjusted Sums of Squares 2761.1
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Using more than one explanatory variable Sequential and Adjusted Sums of Squares
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Using more than one explanatory variable Why use more than one? Intervening or “3rd” variables (schoolchildren’s maths) Reducing error variation (saplings) There is more than one interesting predictor (trees)
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Using more than one explanatory variable Sequential and Adjusted Sums of Squares
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Using more than one explanatory variable Sequential and Adjusted Sums of Squares
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Using more than one explanatory variable Why use more than one? Intervening or “3rd” variables (schoolchildren’s maths) Reducing error variation (saplings) There is more than one interesting predictor (trees)
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Using more than one explanatory variable Sequential and Adjusted Sums of Squares
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Using more than one explanatory variable Sequential and Adjusted Sums of Squares MTB > glm lvol=lhgt; SUBC> covar lhgt. Source DF Seq SS Adj SS Adj MS F P LHGT 1 3.5042 3.5042 3.5042 21.14 0.000 Error 29 4.8080 4.8080 0.1658 Total 30 8.3122 MTB > glm lvol=lhgt+ldiam; SUBC> covar lhgt ldiam. Source DF Seq SS Adj SS Adj MS F P LHGT 1 3.5042 0.1987 0.1987 30.14 0.000 LDIAM 1 4.6234 4.6234 4.6234 701.33 0.000 Error 28 0.1846 0.1846 0.0066 Total 30 8.3122
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Using more than one explanatory variable Models and parameters
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Using more than one explanatory variable Models and parameters Y = + Unknown quantities we would like to know, in Known quantities that are estimates of them, in Latin
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Using more than one explanatory variable Models and parameters Y = +
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Using more than one explanatory variable Models and parameters MTB > glm lvol=ldiam+lhgt; SUBC> covar ldiam lhgt. Analysis of Variance for LVOL, using Adjusted SS for Tests Source DF Seq SS Adj SS Adj MS F P LDIAM 1 7.9289 4.6234 4.6234 701.33 0.000 LHGT 1 0.1987 0.1987 0.1987 30.14 0.000 Error 28 0.1846 0.1846 0.0066 Total 30 8.3122 Term Coef SE Coef T P Constant -6.6467 0.7983 -8.33 0.000 LDIAM 1.98306 0.07488 26.48 0.000 LHGT 1.1203 0.2041 5.49 0.000
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Using more than one explanatory variable Models and parameters MTB > glm lvol=ldiam+lhgt; SUBC> covar ldiam lhgt. Analysis of Variance for LVOL, using Adjusted SS for Tests Source DF Seq SS Adj SS Adj MS F P LDIAM 1 7.9289 4.6234 4.6234 701.33 0.000 LHGT 1 0.1987 0.1987 0.1987 30.14 0.000 Error 28 0.1846 0.1846 0.0066 Total 30 8.3122 Term Coef SE Coef T P Constant -6.6467 0.7983 -8.33 0.000 LDIAM 1.98306 0.07488 26.48 0.000 LHGT 1.1203 0.2041 5.49 0.000 Fitted LVOL = -6.6467 + 1.98306*LDIAM + 1.1203*LHGT
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Using more than one explanatory variable Models and parameters lvol=ldiam+lhgt Model Model Formula Best Fit Equation Fitted LVOL = -6.6467 + 1.98306*LDIAM + 1.1203*LHGT
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Using more than one explanatory variable Models and parameters MTB > glm lvol=ldiam; SUBC> covariate ldiam. Analysis of Variance for LVOL Source DF Seq SS Adj SS Adj MS F P LDIAM 1 7.9254 7.9254 7.9254 599.72 0.000 Error 29 0.3832 0.3832 0.0132 Total 30 8.3087
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Using more than one explanatory variable Models and parameters MTB > glm lvol=ldiam; SUBC> covariate ldiam. Analysis of Variance for LVOL Source DF Seq SS Adj SS Adj MS F P LDIAM 1 7.9254 7.9254 7.9254 599.72 0.000 Error 29 0.3832 0.3832 0.0132 Total 30 8.3087
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Source DF Seq SS Adj SS Adj MS F P LDIAM 1 7.9254 7.9254 7.9254 599.72 0.000 Error 29 0.3832 0.3832 0.0132 Total 30 8.3087 Source DF Seq SS Adj SS Adj MS F P LDIAM 1 7.9254 4.6275 4.6275 698.63 0.000 LHEIGHT 1 0.1978 0.1978 0.1978 29.86 0.000 Error 28 0.1855 0.1855 0.0066 Total 30 8.3087 Using more than one explanatory variable Models and parameters
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Using more than one explanatory variable Geometry in 3-D
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Using more than one explanatory variable Geometry in 3-D Source DF Seq SS Adj SS Adj MS F P LHGT 1 3.5042 0.1987 0.1987 30.14 0.000 LDIAM 1 4.6234 4.6234 4.6234 701.33 0.000 Error 28 0.1846 0.1846 0.0066 Total 30 8.3122 Source DF Seq SS Adj SS Adj MS F P LDIAM 1 7.9289 4.6234 4.6234 701.33 0.000 LHGT 1 0.1987 0.1987 0.1987 30.14 0.000 Error 28 0.1846 0.1846 0.0066 Total 30 8.3122
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Using more than one explanatory variable Geometry in 3-D
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Using more than one explanatory variable Geometry in 1-D
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Using more than one explanatory variable Next week: Designing experiments Read Chapter 5 Two or more x-variables are often useful and often necessary, and are easy to fit Two variables may duplicate or mask each others’ information Seq and Adj SS, plug-in parts, statistical elimination Model, model formula, and best fit equation Last words…
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