Does weather affect the occurrence of violent crimes? Sociologists have long deb

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? Reject the null hypothesis x^2_cal > x^2_.05 = ____ Test Statistic: What is the expected value for the fall season? Expected value for fall = _____ Using SPSS, what is the calculated Chi Square value? Copy the segment of the SPSS output that shows the value. (1) What is the p-value? P-value = ____.

Explanation / Answer

Ans:

H0:homicide rate are same for four season.

H1:homicider rates are different for four seaons.

O=observed

E=Expected

Expected count=1500/4=375

Calculated Chi square=36.133

Critical chi square (for significance level of 0.05 and df=4-1=3 )= 7.815

p-value=0

As,calculated Chi square>critical chi square,We reject null hypothesis.

There is sufficient evidence to support the contention that homicides rates are different for four seasons.

Yes,we have evidence that weather affects the homicides rates i.e. both are not indpendent.

winter spring summer fall Total Number of homicides(O) 328 372 471 329 1500 Number of homicides(E) 375 375 375 375 1500 (O-E)^2/E 5.891 0.024 24.576 5.643 36.133

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