Meadowfoam Example (Data from Sleuth Case Study 9 s1

Meadowfoam Example (Data from Sleuth Case Study 9 s1

<p>Meadowfoam Example (Data from Sleuth Case Study 9.01) meadowfoam = read.csv("../Data/sleuthdata/case0901.csv") summary(meadowfoam) meadowfoam$TIME = meadowfoam$TIME – 1 # recode Timing to be 0/1</p><p>First plot the data! 0 7 s r e w o l 0 6 F</p><p> f o</p><p>#</p><p> e g a r 0 e 5 g v A 0 4 0 3</p><p>200 400 600 800</p><p>Light Intensity</p><p>(Can also use Lattice/Trellis Plots – see DAG R book) library(lattice) xyplot(FLOWERS ~ INTENS | TIME, data=meadowfoam)</p><p>200 400 600 800</p><p>TIME TIME 80</p><p>70 S R</p><p>E 60 W O L F</p><p>50</p><p>40</p><p>30</p><p>200 400 600 800 INTENS</p><p>Assumptions OK? Model E(Avg # flowers) = f( Intensity, Timing)</p><p>Parallel Lines Model:</p><p>> mf.lm1 = lm(FLOWERS ~ INTENS + TIME, data=meadowfoam) > summary(mf.lm1)</p><p>Call: lm(formula = FLOWERS ~ INTENS + TIME, data = meadowfoam)</p><p>Residuals: Min 1Q Median 3Q Max -9.652 -4.139 -1.558 5.632 12.165 </p><p>Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 71.305834 3.273772 21.781 6.77e-16 *** INTENS -0.040471 0.005132 -7.886 1.04e-07 *** TIME 12.158333 2.629557 4.624 0.000146 *** --- Signif. codes: 0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1 </p><p>Residual standard error: 6.441 on 21 degrees of freedom Multiple R-Squared: 0.7992, Adjusted R-squared: 0.78 F-statistic: 41.78 on 2 and 21 DF, p-value: 4.786e-08</p><p>> anova(mf.lm1) Analysis of Variance Table</p><p>Response: FLOWERS Df Sum Sq Mean Sq F value Pr(>F) INTENS 1 2579.75 2579.75 62.182 1.037e-07 *** TIME 1 886.95 886.95 21.379 0.0001464 *** Residuals 21 871.24 41.49 </p><p>Residuals vs Fitted</p><p>2 0 1 6 s 5 l a u d i s e 0 R 5 - 0</p><p>1 9 -</p><p>40 50 60 70</p><p>Fitted values lm(formula = FLOWERS ~ INTENS + TIME, data = meadowfoam) Model with different Slopes and Intercepts:</p><p>> mf.lm2 = lm(FLOWERS ~ INTENS + TIME + INTENS*TIME, data=meadowfoam) > summary(mf.lm2)</p><p>Call: lm(formula = FLOWERS ~ INTENS + TIME + INTENS * TIME, data = meadowfoam)</p><p>Residuals: Min 1Q Median 3Q Max -9.516 -4.275 -1.422 5.473 11.938 </p><p>Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 71.623333 4.343305 16.491 4.14e-13 *** INTENS -0.041076 0.007435 -5.525 2.08e-05 *** TIME 11.523333 6.142361 1.876 0.0753 . INTENS:TIME 0.001210 0.010515 0.115 0.9096 --- Signif. codes: 0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1 </p><p>Residual standard error: 6.598 on 20 degrees of freedom Multiple R-Squared: 0.7993, Adjusted R-squared: 0.7692 F-statistic: 26.55 on 3 and 20 DF, p-value: 3.549e-07 </p><p>> anova(mf.lm2) Analysis of Variance Table</p><p>Response: FLOWERS Df Sum Sq Mean Sq F value Pr(>F) INTENS 1 2579.75 2579.75 59.2597 2.101e-07 *** TIME 1 886.95 886.95 20.3742 0.0002119 *** INTENS:TIME 1 0.58 0.58 0.0132 0.9095676 Residuals 20 870.66 43.53 --- Signif. codes: 0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1 </p><p># Compare Models Parallel lines vs Separate Slopes/Intercepts</p><p>> anova(mf.lm1, mf.lm2) Analysis of Variance Table</p><p>Model 1: FLOWERS ~ INTENS + TIME Model 2: FLOWERS ~ INTENS + TIME + INTENS * TIME Res.Df RSS Df Sum of Sq F Pr(>F) 1 21 871.24 2 20 870.66 1 0.58 0.0132 0.9096 ></p>

View Full Text

Details

  • File Type
    pdf
  • Upload Time
    -
  • Content Languages
    English
  • Upload User
    Anonymous/Not logged-in
  • File Pages
    3 Page
  • File Size
    -

Download

Channel Download Status
Express Download Enable

Copyright

We respect the copyrights and intellectual property rights of all users. All uploaded documents are either original works of the uploader or authorized works of the rightful owners.

  • Not to be reproduced or distributed without explicit permission.
  • Not used for commercial purposes outside of approved use cases.
  • Not used to infringe on the rights of the original creators.
  • If you believe any content infringes your copyright, please contact us immediately.

Support

For help with questions, suggestions, or problems, please contact us