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Transformations

Transformations. Process. Make scatterplot of ( x,y ) Check for linearity Look at residual plot (x, resid ) Check for random scattering of points Look at r 2 Higher r 2  Better model Begin transformations. Linear Transformations. LinReg (log x, y) LinReg (x, log y)

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Transformations

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  1. Transformations

  2. Process • Make scatterplot of (x,y) • Check for linearity • Look at residual plot (x, resid) • Check for random scattering of points • Look at r2 • Higher r2 Better model • Begin transformations

  3. Linear Transformations • LinReg(log x, y) • LinReg(x, log y) • LinReg(log x, log y) • OR… • LinReg(ln x, y) • LinReg(x, ln y) • LinReg(ln x, ln y)

  4. Non-linear Transformations Power Regression Exponential Regression Quadratic Regression Cubic Regression Others that are not necessary to try: QuartReg, LnReg, SinReg

  5. Checklist LinReg(x, y) PwrReg (x, y) LinReg(log x, y) ExpReg (x, y) LinReg(x, log y) QuadReg (x, y) LinReg(log x, log y) CubicReg (x, y) Check Residual Plot first Then, check r2 ALWAYS LOOK AT BOTH!! OR LN instead

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