An experiment was conducted on the growth rates of tree seedlings by selecting seeds

An experiment was conducted on the growth rates of tree seedlings by selecting seeds


Question :



An experiment was conducted on the growth rates of tree seedlings by selecting seeds from 4 varieties of trees (denoted Victoria1, Victoria2, Clinton, and Branch). Four regional blocks were selected where within each block, 1 ha plots were planted with seedlings from each variety. Then within each 1 ha plot, four 100 m2 sub-plots were selected, and one of 4 different sprays were sprayed on the seedlings. These four treatments were denoted as (Check, Ceresan, Panogen, and Agrox). The data can be found found at trees.csv

What is the experimental design?

Create an interaction plot for the variety.

Create an ANOVA table and perform relevant tests.

Is interaction significant? Do your results agree with part (b)?

Do you think it is a good idea to remove a variety from the data and analyze seperately? Explain.

If yes.

How would you analyze the spray for that one variety, i.e. what design would you use? Hint: It might be helpful to visualize the data in wide format.

Analyze the remainder of the data (with that one variety removed). Plot interaction plots, determine which effects are significant and perform pairwise Tukey 95% comparisons.

If no, which effects are significant? Perform pairwise Tukey 95% comparisons