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Thomas Knotts. Engineers often: Regress data  Analysis  Fit to theory  Data reduction Use the regression of others  Antoine Equation  DIPPR.

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Presentation on theme: "Thomas Knotts. Engineers often: Regress data  Analysis  Fit to theory  Data reduction Use the regression of others  Antoine Equation  DIPPR."— Presentation transcript:

1 Thomas Knotts

2 Engineers often: Regress data  Analysis  Fit to theory  Data reduction Use the regression of others  Antoine Equation  DIPPR

3 There are two classes of regressions  Linear  Non-linear “Linear” refers to the parameters, not the functional dependence of the independent variable  You can use the Mathcad function “linfit” on linear equations

4 There are two classes of regressions  Linear  Non-linear “Linear” refers to the parameters, not the functional dependence of the independent variable  You can use the Mathcad function “linfit” on linear equations 1. 2. 3. 4. 5.

5 residual (error) “X” data “Y” predicted slope Intercept

6 residual (error) sum squared error “X” data “Y” data intercept 0.92291455 slope 0.516173934 12.7490321781.4390884831.309943694 23.7199102242.3620030331.357907192 30.9259950173.284917582-2.35892257 42.6234826864.207832132-1.58434945 56.5397973425.1307466811.409050661 66.7799091776.0536612310.726247946 74.9461504016.976575781-2.03042538 89.6741780697.899490331.774687739 97.619598218.82240488-1.20280667 107.6500209969.745319429-2.09529843 1111.51410.668233980.845766021 1213.1828506811.591148531.591702152 1313.2817363512.514063080.767673275 1413.6044459213.436977630.16746829 1512.7953521814.35989218-1.56454 1617.8237477815.282806732.540941056 1714.5506837916.20572128-1.65503748 42.76608602SS E “Y” predicted

7 A useful statistic but not definitive Tells you how well the data fit the model. It does not tell you if the model is correct.

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11 When you fit data to a straight line, the slope and intercept are only estimates of the true slope and intercept.

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14 Linear regression can be written in matrix form. XY 21186 24214 32288 47425 50455 59539 68622 74675 62562 50453 41370 30274

15 Standard Error of b i is the square root of the i-th diagonal term of the matrix


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