A random sample of 104 logs felled at a specialty timber plantation has been selected to study diversity of undergrowth and timber quality. Some of the variables recorded for each log are listed below.

Variable Description subid Subject ID timber wood species numSpecies number of different species of plant observed in the undergrowth within 30m of the tree usable the percentage of the log producing usable timber ageTreeCat the age of tree

Part 1

Research question: we are interested in studying the association between the age of the felled tree and wood species in the population under consideration. Please complete the following tables, calculating the values of A and B.

Observed count | 1 (less than 15) | 2 (16-21) | 3 (22-26) | 4 (more than 26) | Sum blackwood | 13 | 11 | 14 | 16 | 54 sassafras | 14 | 10 | A=*** | 7 | 50 Sum | 27 | 21 | 33 | 23 | 104

Expected count | 1 (less than 15) | 2 (16-21) | 3 (22-26) | 4 (more than 26) blackwood | B=*** | 10.904 | 17.135 | 11.942
sassafras | 12.981 | 10.096 | 15.865 | 11.058

chi-squared | 1 (less than 15) | 2 (16-21) | 3 (22-26) | 4 (more than 26) blackwood | 0.074 | 0.001 | 0.573 | 1.379
sassafras | 0.08 | 0.001 | 0.619 | 1.489
A [integer]: Answer 1 Question 1 B [use at least 3dp]: Answer 2 Question 1

A chi-squared test of independence is run to answer the research question. Consider the output of the test below, and answer the questions:

Pearson's Chi-squared test

data: table(var1, var4) X-squared = 4.2164, df = 3, p-value = 0.239 What is the null hypothesis? Choose one among the following options: a. the age of tree felled at a specialty timber plantation is not distributed according to the given table of probabilities b. the age of tree is associated with wood species c. the age of tree and wood species are independent d. the age of tree felled at a specialty timber plantation is distributed according to the given table of probabilities Answer 3 Question 1

From the p-value as reported above, we can conclude that the decision of the test is: Answer 4 Question 1

What is the conclusion of the test? a. There is evidence that the age of tree and wood species are associated b. There is evidence that the age of tree felled at a specialty timber plantation is not distributed according to the given table of probabilities c. There is not enough evidence that the age of tree felled at a specialty timber plantation is distributed differently than the given table of probabilities d. There is evidence that the age of tree felled at a specialty timber plantation is not distributed according to the given table of probabilities e. There is evidence that the age of tree and wood species are independent f. There is not evidence that the age of tree and wood species are associated g. There is evidence that the age of tree felled at a specialty timber plantation is distributed according to the given table of probabilities Answer 5 Question 1