In: Statistics and Probability
An irrigation experiment was conducted in a randomized complete block design in a Lavencia orange grove. Six irrigation treatments were used in eight blocks of trees. The data below are the weight in pounds of harvested fruit from each plot.
a. Consider the flood irrigation method to be the standard practice. Use the Dunnett method to test the difference between the flood irrigation and each of the other methods
b. Calculate the F-statistic assuming a completely randomized one-way design. How different are the results?
c. Check the assumptions from part b. Make sure to include any plots in your solutions
method | block | weight |
trickle | 1 | 450 |
trickle | 2 | 469 |
trickle | 3 | 249 |
trickle | 4 | 125 |
trickle | 5 | 280 |
trickle | 6 | 352 |
trickle | 7 | 221 |
trickle | 8 | 251 |
Basin | 1 | 358 |
Basin | 2 | 512 |
Basin | 3 | 281 |
Basin | 4 | 58 |
Basin | 5 | 352 |
Basin | 6 | 293 |
Basin | 7 | 283 |
Basin | 8 | 186 |
Spray | 1 | 331 |
Spray | 2 | 402 |
Spray | 3 | 183 |
Spray | 4 | 70 |
Spray | 5 | 250 |
Spray | 6 | 281 |
Spray | 7 | 219 |
Spray | 8 | 46 |
Sprinkler | 1 | 317 |
Sprinkler | 2 | 423 |
Sprinkler | 3 | 379 |
Sprinkler | 4 | 63 |
Sprinkler | 5 | 289 |
Sprinkler | 6 | 239 |
Sprinkler | 7 | 269 |
Sprinkler | 8 | 357 |
Sprinkler+Spray | 1 | 479 |
Sprinkler+Spray | 2 | 341 |
Sprinkler+Spray | 3 | 404 |
Sprinkler+Spray | 4 | 115 |
Sprinkler+Spray | 5 | 182 |
Sprinkler+Spray | 6 | 349 |
Sprinkler+Spray | 7 | 276 |
Sprinkler+Spray | 8 | 182 |
Flood | 1 | 245 |
Flood | 2 | 380 |
Flood | 3 | 263 |
Flood | 4 | 62 |
Flood | 5 | 336 |
Flood | 6 | 282 |
Flood | 7 | 171 |
Flood | 8 | 98 |
a. Consider the flood irrigation method to be the standard practice. Use the Dunnett method to test the difference between the flood irrigation and each of the other methods
Using the Dunnett Method and 95% Confidence
method | N | Mean | Grouping |
Basin (control) | 8 | 290.4 | A |
trickle | 8 | 299.6 | A |
Sprinkler | 8 | 292.0 | A |
Sprinkler+Spray | 8 | 291.0 | A |
Flood | 8 | 229.6 | A |
Spray | 8 | 222.8 | A |
Means not labeled with the letter A are significantly different from the control level mean.
b. Calculate the F-statistic assuming a completely randomized one-way design. How different are the results?
Analysis of Variance
Source | DF | Adj SS | Adj MS | F-Value | P-Value |
method | 5 | 48605 | 9721 | 2.32 | 0.064 |
block | 7 | 457328 | 65333 | 15.60 | 0.000 |
Error | 35 | 146575 | 4188 | ||
Total | 47 | 652508 |
The F-statist ic is 2.32.
The results are not significant.
c. Check the assumptions from part b. Make sure to include any plots in your solutions
The assumptions are met.