Researchers watched groups of dolphins off the coast of Ireland in 1998 to deter
ID: 2946507 • Letter: R
Question
Researchers watched groups of dolphins off the coast of Ireland in 1998 to determine what activities the dolphins partake in at certain times of the day ("Activities of dolphin," 2013). The numbers in table below represent the number of groups of dolphins that were partaking in an activity at certain times of days:
Table: Dolphin Activity
Activity
Period
Row
Total
Morning
Noon
Afternoon
Evening
Travel
6
6
14
13
39
Feed
28
4
0
56
88
Social
38
5
9
10
62
Column Total
72
15
23
79
189
Is there enough evidence to show that the activity and the time period are independent for dolphins? Test at the 1% level.
(i) Which of the following statements correctly defines the null hypothesis HO?
A. the activity for dolphins is independent of the time period
B. the activity for dolphins is not independent of the time period
C. neither of these statements is correct for HO
Enter letter corresponding to correct answer
(ii) Which of the following statements correctly defines the alternate hypothesis HA?
A. the activity for dolphins is independent of the time period
B. the activity for dolphins is not independent of the time period
C. neither of these statements is correct for HA
Enter letter corresponding to correct answer
(iii) Enter the level of significance ? used for this test:
Enter in decimal form. Examples of correctly entered answers: 0.01 0.02 0.05 0.10
(iv) Are any of the expected frequency values (for which HO is true) for any cell in your table less than 5? Calculate the expected frequencies using technology, the select most correct answer:
A. yes - this will not affect results of hypothesis test
B. yes - this may invalidate results of hypothesis test
C. no - this will not affect results of hypothesis test
D. no - this may invalidate results of hypothesis test
Enter letter corresponding to correct answer. Recommend using the following applet ( Chi-Square Test of Independence Applet) to create contingency table of expected and observed frequency values in order to answer this question.
(v) Using calculator, spreadsheet, or online calculator, determine test statistic:
Enter value in decimal form rounded to nearest thousandth. Examples of correctly entered answers:
2.010 0.307 1.600 11.019
Recommended online calculator: Chi-Square Test of Independence Applet
(vi) Using tables, calculator, or spreadsheet: Determine and enter p-value corresponding to test statistic.
Enter value in decimal form rounded to nearest ten-thousandth. Examples of correctly entered answers:
0.0001 0.0021 0.0305 0.6004 0.8143 1.0000
Recommended online calculator: Chi-Square Test of Independence Applet
(vii) Comparing p-value and ? value, which is the correct decision to make for this hypothesis test?
A. Reject Ho
B. Fail to reject Ho
C. Accept Ho
D. Accept HA
Enter letter corresponding to correct answer.
(viii) Select the statement that most correctly interprets the result of this test:
A. The result is not statistically significant at .01 level of significance. Sufficient evidence exists to support the claim that the activity and the time period are NOT independent for dolphins.
B. The result is not statistically significant at .01 level of significance. There is not enough evidence to support the claim that the activity and the time period are NOT independent for dolphins.
C. The result is statistically significant at .01 level of significance. There is not enough evidence to support the claim that the activity and the time period are NOT independent for dolphins.
D. The result is statistically significant at .01 level of significance. Sufficient evidence exists to support the claim that the activity and the time period are NOT independent for dolphins.
Enter letter corresponding to most correct answer
Activity
Period
Row
Total
Morning
Noon
Afternoon
Evening
Travel
6
6
14
13
39
Feed
28
4
0
56
88
Social
38
5
9
10
62
Column Total
72
15
23
79
189
Explanation / Answer
1)
A. the activity for dolphins is independent of the time period
2)
B. the activity for dolphins is not independent of the time period
3)
Let the Los be Alfa = 0.01
4)
B. yes - this may invalidate results of hypothesis test
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