Skip directly to search Skip directly to A to Z list Skip directly to page options Skip directly to site content

Volume 8, Number 4—April 2002

Research

Sampling Bias in the Molecular Epidemiology of Tuberculosis

Megan MurrayComments to Author 
Author affiliation: Harvard School of Public Health, Boston, Massachusetts, USA

Main Article

Table 2

Monte Carlo means and 95% ranges for the proportion of unique isolates and for odds ratios after sampling a fraction of the complete data set.

Sampling fraction 1 0.7 0.5 0.1
Sudan
Proportion of reactivated isolates
n method 0.18 0.19 (0.18-0.19) 0.21 (0.19-0.23) 0.37 (0.30-0.43)
“n minus one” method 0.28 0.32 (0.30-0.34) 0.35 (0.30-0.41) 0.54 (0.47-0.62)
Odds ratiosa 2 1.88 (1.87-1.97) 1.77 (1.66-1.88) 1.34 (1.28-1.45)
5 4.18 (4.13-4.78) 3.51 (3.01-4.18) 1.84 (1.60-2.18)
10 7.52 (7.38-9.27) 1.84 (1.67-1.84) 2.37 (2.08-2.99)
New York prisons
Proportion of reactivated isolates
n method 0.12 0.14 (0.12-0.16) 0.16 (0.13-0.20) 0.45 (0.28-0.62)
“n minus one” method 0.33 0.36 (0.33-0.38) 0.39 (0.32-0.45) 0.67 (0.61-0.73)
Odds ratios 2 1.77 (1.60-1.95) 1.62 (1.45-1.83) 1.16 (1.12-1.29)
5 3.51 (2.73-4.58) 2.78 (2.18-3.83) 1.37 (1.25-1.37)
10 5.79 (4.07-8.66) 4.17 (2.99-6.58) 1.58 (1.39-2.12)
Algeria
Proportion of reactivated isolates
n method 0.43 0.48 (0.45-0.51) 0.16 (0.13-0.20) 0.45 (0.28-0.62)
“n minus one” method 0.65 0.71 (0.69-0.74) 0.76 (0.69-0.83) 0.92 (0.81-0.99)
Odds ratios 2 1.81 (1.75-1.92) 1.67(1.45-1.97) 1.29 (1.18-1.73)
5 3.68 (2.79-4.82) 3.02 (2.99-4.73) 1.98 (1.77-2.33)
10 6.58 (5.55-8.23) 5.05 (4.17-6.58) 2.62 (2.26-3.28)
U.S. prisons
Proportion of reactivated isolates
n method 0.29 0.33 (0.29-0.39) 0.37 (0.29-0.48) 0.68 (0.35-1.00)
“n minus one” method 0.33 0.35 (0.31-0.38) 0.37 (0.32-0.41) 0.62 (0.50-0.73)
Odds ratios 2 1.8 (1.62-1.98) 1.67 (1.45-1.97) 1.29 (1.18-1.73)
5 3.68 (2.79-4.82) 3.02 (2.99-4.73) 2.11 (1.62-5.31)
10 6.86 (5.30-9.66)) 4.67 (3.02-9.13) 2.11 (1.62-5.31)
Netherlands
Proportion of reactivated isolates
n method 0.49 0.62 (0.55-0.69) 0.62 (0.55-0.69) 0.89 (0.77-1.00)
“n minus one” method 0.65 0.78 (0.72-0.85) 0.78 (0.72-0.85) 0.93 (0.79-1.00)
Odds ratios 2 1.8 (1.62-1.98) 1.67 (1.57-1.81) 1.40 (1.31-1.49)
5 3.68 (2.79-4.82) 3.05 (2.63-3.78) 2.02 (1.79-2.32)
10 6.86 (5.30-9.66)) 4.76 (3.86-6.47) 3.86 (2.39-3.25)

aConfidence intervals for odds ratios are based on the results of 2 by 2 tables, with data adjusted for the mean misclassification introduced by sampling.

Main Article

TOP