Skip directly to search Skip directly to A to Z list Skip directly to site content
CDC Home

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 of Page

USA.gov: The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30333, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO