Question

Year	Total Tornadoes
1950	213
1951	272
1952	252
1953	434
1954	562
1955	605
1956	516
1957	870
1958	576
1959	616
1960	628
1961	709
1962	669
1963	475
1964	716
1965	909
1966	597
1967	938
1968	672
1969	620
1970	666
1971	901
1972	753
1973	1114
1974	957
1975	931
1976	846
1977	864
1978	801
1979	867
1980	878
1981	794
1982	1059
1983	943
1984	919
1985	696
1986	777
1987	668
1988	714
1989	868
1990	1145
1991	1144
1992	1309
1993	1185
1994	1094

Open Tornadoes-HW12 data. Is it reasonable to claim that the average annual number of tornadoes occurred until 1970 (inclusive) was significantly different from the average annual number of tornadoes occurred after 1970?

6. What test/procedure did you perform? (5 points)

• a. One-sided t-test
• b. Two-sided t-test
• c. Regression
• d. Confidence Interval

7. What would be the correct Null-Hypothesis? (hint read end of lecture 24) (5 points)

• a. average annual number of tornadoes occurred until 1970 (inclusive) and average annual number of tornadoes occurred after 1970 are different.
• b. average annual number of tornadoes occurred until 1970 (inclusive) and average annual number of tornadoes occurred after 1970 are equal.
• c. average annual number of tornadoes occurred until 1970 (inclusive) and average annual number of tornadoes occurred after 1970 are related.
• d. average annual number of tornadoes occurred until 1970 (inclusive) and average annual number of tornadoes occurred after 1970 are not related.

8. What is the P-value/margin of error and what can be statistically concluded about the Null Hypothesis? (hint read end of lecture 24) (5 points)

• a. 4.19782 and we do not reject the Null Hypothesis
• b. 2.09891E-07 and we accept the Null Hypothesis
• c. 4.19782E-07 and we reject the Null Hypothesis
• d. 4.161353 and we accept the Null Hypothesis

9. What is the Statistical interpretation? (5 points)

• a. The P-value is much smaller than 5% thus we are very certain that the slope is not zero.
• b. The P-value is much smaller than 5% thus we are confident to say that the averages are significantly different.
• c. The P-value is greater than 5% thus we cannot claim that the averages are different.
• d. None of these.

10. What is the conclusion? (5 points)

• a. We are confident that the average annual number of tornadoes occurred until 1970 (inclusive) was significantly different from the average annual number of tornadoes occurred after 1970.
• b. We cannot be confident that the average annual number of tornadoes occurred until 1970 (inclusive) was significantly different from the average annual number of tornadoes occurred after 1970.
• c. The result is inconclusive thus we cannot conclude anything.
• d. None of these.

Task 1

Answer 1

Ans 6

Since we need to compare average of two data, we will be using Two Sided t-test

Option B

Ans 7

Correct Null Hypotheses:

1(till 1970) = 2(after 1970)

Which means Option B

Ans 8

Assuming variances to be unequal, please find the summary below:

Option C is correct

Ans 9

Since p-value is much smaller than 5%, we can say average is significantly different

Option B

Ans 10

Option A