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 | 23 | 20 | 15 | 17 | 75
sassafras | 28 | 13 | 15 | A=*** | 70
Sum | 51 | 33 | 30 | 31 | 145
Expected count
| 1 (less than 15) | 2 (16-21) | 3 (22-26) | 4 (more than 26)
blackwood | 26.379 | 17.069 | B=*** | 16.034
sassafras | 24.621 | 15.931 | 14.483 | 14.966
chi-squared
| 1 (less than 15) | 2 (16-21) | 3 (22-26) | 4 (more than 26)
blackwood | 0.433 | 0.503 | 0.017 | 0.058
sassafras | 0.464 | 0.539 | 0.018 | 0.062
A [integer]:
B [use at least 3dp]:
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 = 2.0954, df = 3, p-value = 0.5528
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 felled at a specialty timber plantation is distributed according to the given table of probabilities
c. the age of tree and wood species are independent
d. the age of tree is associated with wood species
From the p-value as reported above, we can conclude that the decision of the test is:
What is the conclusion of the test?
a. 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
b. There is evidence that the age of tree felled at a specialty timber plantation is distributed according to the given table of probabilities
c. There is evidence that the age of tree and wood species are associated
d. There is not evidence that the age of tree and wood species are associated
e. There is evidence that the age of tree and wood species are independent
f. There is evidence that the age of tree felled at a specialty timber plantation is not distributed according to the given table of probabilities