BTS | TABLE 1 - Comparison of Sampling Strategies

TABLE 1 - Comparison of Sampling Strategies

Sampling and estimation alternative	Unstratified ratio estimation statistics			Overall performance
Sampling and estimation alternative	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.