An insurance investigator has observed people with some astrological signs tend to be safer drivers people with other signs. Using insurance records, the investigator classified 200 people according to their astrological signs as well as whether or not they were involved in car accident throughout the previous 12 months. The data are as follows:
Libra Leo Gemini
Accident 7 4 19
No Accident 73 46 51
Do the data indicate a significant relationship between sign and accidents? Test at the .05 level of significance.
Answers
A. The null hypothesis states that there is no difference between the proportion of accidents for the three groups. With a = .05 and df = 2, the critical value is 12.47. For these data, chi-squared = 5.99. Fail to reject H0 and conclude that there are no significant differences in accident rates for the three signs.
B. The null hypothesis states that there is no difference between the proportion of accidents for the three groups. With a = .05 and df = 2, the critical value is 5.99. For these data, chi-squared = 12.47. Reject H0 and conclude that there are significant differences in accident rates for the three signs.
C. The null hypothesis states that there is no difference between the proportion of accidents for the three groups. With a = .05 and df = 6, the critical value is 12.59. For these data, chi-squared = 12.47. Fail to reject H0 and conclude that there are no significant differences in accident rates for the three signs.
D. The null hypothesis states that there is no difference between the proportion of accidents for the three groups. With a = .05 and df = 2, the critical value is 5.99. For these data, chi-squared = 6.00. Reject H0 and conclude that there are significant differences in accident rates for the three signs.