TABLE 1 - Comparison of Sampling Strategies

TABLE 1 - Comparison of Sampling Strategies

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Sampling and estimation alternative Unstratified ratio estimation statistics Overall performance
cv of pass-miles cv of auxiliary variable Correlation coeff between pass-miles and auxiliary variable Unit cv Necessary sample size (SS) SS reduction vs. Circular
– Circular 2710.1A       n.a. 549  
A Direct sampling and estimation       0.95 522 5%
B Ratio estimation; auxiliary variable = boardings 0.95 0.77 0.67 0.72 296 46%
C Stratified ratio estimation (4 strata); auxiliary variable = boardings       0.43 117 79%
D Combined ratio estimation; auxiliary variable = boardings       0.45 117 79%
E Ratio estimation; auxiliary variable = (boardings * route length) 0.95 0.91 0.89 0.44 112 80%
F Ratio estimation; auxiliary variable = (boardings * adjusted route length) 0.95 1.09 0.89 0.51 147 73%
G Combined ratio estimation; auxiliary variable = (boardings * route length)       0.39 86 84%

KEY: cv = coefficient of variation.