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Statistics 200b. Chapter 5. Chapter 4: inference via likelihood now Chapter 5: applications to particular situations
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annual max sea levels 1931-81 Y: max cm x: year
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5.1 Straight-line regression. How one variable depends on others Response, Y, random Explanatories, x, fixed (covariates)
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Reparametrize. Simplifies several things
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Likelihood analysis.
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Distributions. j : IN(0, 2 ) Linear combinations of normals
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Venice sea level. n = 51
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Prediction. at x +
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Example.
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annual max sea levels 1931-81 Y: max cm x: year
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(Raw) residuals.
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Stat 200b. Chapter 8. Linear regression models.
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n by 1, n by 2, 2 by 1, n by 1
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13 by 5
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Effect of increasing seat height is 2 1
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Some matrix review transpose multiplication inverse derivatives
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Normal linear model. Estimation
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Profile log likelihood
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Straight-line/simple regression.
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Fitted values. NB. Assuming matrix inverse exists
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Weighted least squares. inverse existing
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Example 8.8. Cycling data
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Example 8.10. Maize data.
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Likelihood quantities.
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Take expected values
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Normal distribution theory. Full rank case
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A useful decomposition.
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Confidence interval.
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Gauss-Markov Theorem. page 374
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There is a generalized inverse variant Example.
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Eg. Teaching methods data, p. 427 Method average Usual 17 14 24 20 24 … 24 19.67 Praised 28 30 29 24 27 … 23 27.41 two-sample model / one-way layout
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Robust/resistant estimators outlier - observation that is unusual compared to others resistant statistic - not strongly affected by outliers robust estimate - performs well under a range of potential models centered at an ideal model
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13 by 5
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ANOVA table
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13 by 5
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Model 1: y ~ 1 Model 2: y ~ x1 Model 3: y ~ x1 + x2 Model 4: y ~ x1 + x2 + x3 Model 5: y ~ x1 + x2 + x3 + x4 Res.Df RSS Df Sum of Sq F Pr(>F) 1 12 2715.76 2 11 1265.69 1 1450.08 242.3679 2.888e-07 *** 3 10 57.90 1 1207.78 201.8705 5.863e-07 *** 4 9 48.11 1 9.79 1.6370 0.2366 5 8 47.86 1 0.25 0.0413 0.8441 Model 1: y ~ 1 Model 2: y ~ x4 Model 3: y ~ x4 + x3 Model 4: y ~ x4 + x3 + x2 Model 5: y ~ x4 + x3 + x2 + x1 Res.Df RSS Df Sum of Sq F Pr(>F) 1 12 2715.76 2 11 883.87 1 1831.90 306.1859 1.161e-07 *** 3 10 175.74 1 708.13 118.3577 4.509e-06 *** 4 9 73.81 1 101.92 17.0356 0.00331 ** 5 8 47.86 1 25.95 4.3375 0.07082
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