Exercise 2 determine whether there are differences in

Exercise 2
Determine whether there are differences in the weights of chickens according to their feed in the chickwts
data. Perform appropriate model diagnostics.
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Theoretical Quantiles
Standardized residuals
lm(weight ~ feed)
Normal Q-Q
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200 250 300
0.0
0.5
1.0
1.5
Fitted values
Standardized residuals
lm(weight ~ feed)
Scale-Location
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0.00 0.02 0.04 0.06 0.08 0.10
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Leverage
Standardized residuals
lm(weight ~ feed)
Cook's distance
Residuals vs Leverage
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TukeyHSD ( aov (weight ~ feed, data = chickwts)) $ feed
## diff lwr upr p adj
## horsebean-casein -163.383333 -232.346876 -94.41979 3.070197e-08
## linseed-casein -104.833333 -170.587491 -39.07918 2.100151e-04
## meatmeal-casein -46.674242 -113.906207 20.55772 3.324584e-01
## soybean-casein -77.154762 -140.517054 -13.79247 8.365309e-03
## sunflower-casein 5.333333 -60.420825 71.08749 9.998902e-01
## linseed-horsebean 58.550000 -10.413543 127.51354 1.413329e-01
## meatmeal-horsebean 116.709091 46.335105 187.08308 1.062092e-04
## soybean-horsebean 86.228571 19.541684 152.91546 4.216654e-03
## sunflower-horsebean 168.716667 99.753124 237.68021 1.219887e-08
## meatmeal-linseed 58.159091 -9.072873 125.39106 1.276965e-01
## soybean-linseed 27.678571 -35.683721 91.04086 7.932853e-01
## sunflower-linseed 110.166667 44.412509 175.92082 8.843233e-05
## soybean-meatmeal -30.480519 -95.375109 34.41407 7.391356e-01
## sunflower-meatmeal 52.007576 -15.224388 119.23954 2.206962e-01
## sunflower-soybean 82.488095 19.125803 145.85039 3.884521e-03
When performing model diagnostics we see that our linearity assumption is valid, the distri-
bution of our errors appears to be normal, and homoscedasticity is present. Our anova table
gives us a p-value way below the .05 threshold. When using our TukeyHSD function we find