11.2 VARIANCE TEST Test statistic about population variance; x2 = (n-1) $2 62 Consider the following issue. London Bus Company hopes its drivers running on schedules within arrival time variance less than 3.0 min. From randomly selected 16 arrivals at City Hall station, the variance was found as s2 = 3.7 min. Is it excessive? Bus Company wants judgment with significance level of a =0.05. x2 = (n-1) $2 15X3.7 = 18.5 3.0 which is smaller than x =25.0 (for d.f.=15). Therefore, from this testing, it is concluded that London Bus drivers are running on schedules.[2] Check again the 'running on schedule' problem above. After secondary examination on 11 arrivals at London Museum, the arrival time variance was found as 32 = 4.1 minz. What is your opinion? (hint: compare the acquired x2 value with 1235 and X231 for d.f.=10)