Question

Parrotfish predate on coral reefs. There are nearly 100 known species of parrotfish; in a particular tropical archepelago, there are two dominant species. In this same area, there are three common species of coral.

Marine ecologists wondered if the parrotfish have different preferences across the coral species. In a 24hr window, divers recorded the number of instances that corals were observed to be predated by the fish. Here are the data:

	Coral sp A	Coral sp B	Coral sp C
Parrotfish sp 1	6	2	14
Parrotfish sp 2	7	21	1

On your own, complete the 10 steps for this problem. Then, complete the following questions in this module.

Step 2: What is the null hypothesis? Select all that are correct.

• A.

  All pi are equal.

• B.

  Not all pi are equal.

• C.

  The parrotfish species have the same distribution of predation across corals.

• D.

  The parrotfish species do not have the same distribution of predation across corals.

Step 3: What is the alternative hypothesis? Select all that are correct.

• A.

  All pi are equal.

• B.

  Not all pi are equal.

• C.

  The parrotfish species have the same distribution of predation across corals.

• D.

  The parrotfish species do not have the same distribution of predation across corals.

Step 4: What is the correct level of alpha?

• A.

  We will use α/2=0.025 to define χ2CRIT and extreme values of χ2OBS in either tail will reject the null.

• B.

  If χ2OBS exceeds χ2CRIT in the right tail of the χ2 distribution, defined by α=0.05, we will reject the null.

• C.

  If χ2OBS is less than χ2CRIT in the left tail of the χ2 distribution, defined by α=0.05, we will reject the null.

Step 5: Which statistical test are you using?

• A.

  χ2 Extrinsic Goodness of Fit test

• B.

  χ2 Intrinsic Goodness of Fit test

• C.

  χ2 Contingency Table test

• D.

  ANOVA

• E.

  Tukey's Honestly Significant Difference test

• F.

  Bonferonni's t-test

Step 6, part I: What is the value of E13? Round to two decimal places in your final answer.

Step 6, part II: What is the value of the test statistic? Round your final answer to two decimal places.

Step 7: What is the value of χ2CRIT? Give your answer to two decimal places.

Step 8: How does the test statistic compare to the critical value?

• A.

  The test statistic is greater than the critical value, and in the critical zone.

• B.

  The test statistic is less than the critical value, and in the critical zone.

• C.

  The test statistic is greater than the critical value, and outside the critical zone.

• D.

  The test statistic is less than the critical value, and outside the critical zone.

Step 9: Based on this comparison, do you accept or reject your null hypothesis?

• A.

  Accept

• B.

  Reject

Step 10: What do you conclude from this analysis? Choose all that are correct.

• A.

  The parrotfish species have the same distribution of predation across corals.

• B.

  The parrotfish species do not have the same distribution of predation across corals.

• C.

  All pi are equal.

• D.

  At least one pi is not equal to the others.

Answer 1