Does weather affect the occurrence of violent crimes? Sociologists have long deb
ID: 3295151 • Letter: D
Question
Does weather affect the occurrence of violent crimes? Sociologists have long debated whether certain atmospheric conditions are associated with increases in the homicide rate. A researcher classified 1,500 homicides in the southwest region of the United States according to the seasons in which the homicide occurred. Use SPSS, the data set is PROB4.sav. a. Do the data support the contention that the homicide rates are different for the four seasons? Write down the null and alternate hypotheses. State the critical value. Use alpha = 0.05. b. Does your conclusion from (a) lend evidence to support the sociologists' contention that weather affects homicide rate? H_o: __________ (2) H_s: _________ (2) Reject the null hypothesis if chi^2_cal > chi^2_.05/1 = Test Statistic: (4) What is the expected value for the fall season? Expected value for fall = __________ (4) Using SPSS, what is the calculated Chi Square value? chi^2_cal = __________ Copy the segment of the SPSS output that shows the value. (1) What is the p-value? P-value = _________ Result: (1) Conclusion:Explanation / Answer
Solution:
a) Test Hypothesis: H0: p1 = p2 = p3 = p4
Ha: at least one of the proportions is different
df = n-1 = 4-1 = 3
Critical value at 5% level and df = 3 is 2 0.05(3) = 7.8147
(2) Reject H0 if caculated 2 >7.8147
b) (4) The expected value of fall season = 375
Calculated 2 = 36.133
p-value = 0.000
as p-value <0.05 and calculated Chi- square = 7.8147, we reject the nukk hypothesis and conclude that the homicide rates are different for thr four seasons
Season
Observed N
Expected N
Residual
Winter
Spring
Summer
Fall
Total
328
372
471
329
1500
375.0
375.0
375.0
375.0
-47.0
-3.0
96.0
-46.0
Test Statistics
Season
Chi-square
df
Asymp.Sig.
36.133^a
3
0
Observed N
Expected N
Residual
Winter
Spring
Summer
Fall
Total
328
372
471
329
1500
375.0
375.0
375.0
375.0
-47.0
-3.0
96.0
-46.0
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