Intro to Quantitative Ecology

Week 08 Pre-Class Assignment

Readings

These questions cover materials in:

• Gardener chapter 8
• Gardener chapter 9

Questions

Question 1

Instructions

For the following equations, select the most appropriate family of correlation

Questions

Multiple choice: 1 pt

\(y = 19.85 + 0.5 \times ln(x)\)

• The most appropriate family is select the best answer linear regression logarithmic correlation linear correlation power-law correlation polynomial correlation negative exponential correlation

Multiple choice: 1 pt

\(y = 244.5 + -23.7x\)

• The most appropriate family is select the best answer linear regression logarithmic correlation linear correlation power-law correlation polynomial correlation negative exponential correlation

Multiple choice: 1 pt

\(y = 23.7 + 1.17x + 0.3x^2\)

• The most appropriate family is select the best answer linear regression logarithmic correlation linear correlation power-law correlation polynomial correlation negative exponential correlation

Question 2

Short answer: 3 pts

• Explain why a statistically significant correlation doesn’t necessarily imply causation.
• You need to use a concrete example (real or made up) of a situation where you might find a significant correlation that is not due to causation.

Question 3

Instructions

Consider the following plot and select the most appropriate correlation type.

Multiple Choice: 1 pt. 

The most appropriate correlation to use for the data summarized in the scatterplot is: Pearson correlation Spearman correlation

Question 4

Instructions

Consider this hypothetical scenario:

A tree survey was conducted to assess the risk of wind damage to trees in Amherst.

Trees were classified into three tree failure risk categories: low risk, medium risk, and high risk.

After a heavy windstorm, a follow-up survey was conducted to assess the trees for failure. Trees were classified as either failed (major damage to the large branches or the entire tree) or intact (little or no damage).

You arrange the data into the following table:

	failed	intact
low risk	19	35
med risk	34	55
high risk	11	9

You want to know whether your risk rating system was effective. In other words, you would like to know whether there is an association between your risk ratings and tree failures.

Multiple Choice: 1 pt

Of the following, what is the most appropriate statistical test?

Analysis of Variance Poisson regression chi-squared test contingency table Spearman correlation Pearson correlation

Submit to Moodle

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