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Volume 11, Number 2—February 2005

Dispatch

Comparing Aberration Detection Methods with Simulated Data

Lori Hutwagner*Comments to Author , Timothy Browne*, G. Matthew Seeman*, and Aaron T. Fleischauer*
Author affiliations: *Centers for Disease Control and Prevention, Atlanta, Georgia, USA

Main Article

Table A1

Sensitivity (sen), specificity (spe) and time to detection (ttd) by method and dataset; to make further comparisons, data can be downloaded by dataset name from http://www.bt.cdc.gov/surveillance/ears/.

Dataset* Trend† Seas‡ Mean§ SD§ Seasonally adjusted CUSUM¶
Historical Limits#
C1–MILD**
C2–MEDIUM††
C3–ULTRA‡‡
sen (%) spe (%) ttd§§ sen (%) spe (%) ttd§§ sen (%) spe (%) ttd§§ sen (%) spe (%) ttd§§ sen (%) spe (%) ttd§§
S01 Yes Low 90 33 96.55 67.54 0.49 79.10 90.64 2.00 42.80 97.47 1.78 54.37 97.59 1.98 71.54 96.05 1.93
S02 No Med 30 6 70.45 98.74 2.32 7.00 99.77 5.60 50.56 98.10 1.53 64.38 98.14 1.79 79.66 96.54 1.70
S03 No Low 1 6 94.58 86.49 0.64 69.67 96.84 2.53 72.68 90.91 0.95 79.07 91.20 0.98 83.58 90.98 0.99
S04 Yes Very 6 4 95.49 83.82 0.68 70.75 96.41 2.41 75.36 97.16 0.92 87.31 96.94 1.06 92.53 95.04 0.97
S05 No Very 38 13 86.98 93.95 1.42 43.00 99.79 4.05 52.38 97.50 1.51 66.23 97.46 1.73 80.21 95.64 1.62
S06 Yes Very 1 6 92.98 90.41 0.64 69.79 98.32 2.24 81.23 94.76 0.42 88.83 94.29 0.57 93.03 92.91 0.56
S07 No Low 150 27 57.63 98.88 2.76 1.64 100.00 6.04 39.77 98.10 1.77 53.11 98.16 2.05 71.23 96.59 1.97
S08 No Very 90 33 88.58 95.06 1.17 51.69 99.61 3.50 63.59 97.48 1.09 78.81 97.46 1.32 87.41 95.73 1.18
S09 Yes Low 30 6 98.70 64.49 0.29 80.00 96.89 2.03 75.36 98.38 1.04 89.48 98.42 1.21 93.45 96.94 1.02
S10 No Low 30 6 67.30 98.32 2.42 5.34 99.68 5.65 45.42 98.00 1.67 57.74 98.05 1.89 75.28 96.51 1.85
S11 Yes Med 301 79 99.16 22.41 0.06 94.45 46.78 0.48 62.23 98.09 1.03 79.70 98.12 1.28 86.68 96.52 1.12
S12 Yes Med 6 4 88.12 96.69 1.40 48.91 99.64 3.81 74.44 96.01 0.97 83.74 96.00 1.09 89.75 94.56 1.02
S13 No Very 150 27 68.41 99.17 2.33 8.97 100.00 5.53 51.64 98.09 1.40 67.87 98.09 1.66 82.41 96.37 1.59
S14 No Med 38 13 83.39 93.32 1.66 31.30 99.89 4.59 43.41 97.54 1.80 55.11 97.64 1.99 72.35 96.03 1.93
S15 Yes Low 6 4 99.64 27.15 0.10 96.91 35.95 0.41 47.66 97.06 1.75 57.93 97.18 1.90 73.14 95.62 1.87
S16 No Low 6 4 92.80 83.13 0.97 62.86 96.88 2.94 50.12 95.83 1.67 57.75 95.97 1.83 71.35 94.55 1.80
S17 Yes Very 90 33 90.31 91.59 0.77 63.72 98.86 2.66 73.89 97.52 0.72 85.20 97.37 0.89 89.09 95.43 0.79
S18 Yes Low 75 21 83.87 92.74 1.56 30.40 99.91 4.54 41.14 97.74 1.80 52.65 97.81 2.05 70.43 96.22 2.00
S19 Yes Very 90 33 81.62 99.62 1.59 41.78 99.86 3.94 80.28 96.85 0.61 90.33 96.57 0.76 93.14 94.81 0.66
S20 No Med 1 6 93.70 91.14 0.72 70.80 99.01 2.29 76.67 93.83 0.48 82.81 93.62 0.63 88.78 92.87 0.68
S21 Yes Very 75 21 91.76 92.69 1.06 54.16 99.55 3.42 62.29 97.81 1.19 78.50 97.65 1.41 87.29 95.77 1.28
S22 No Low 38 13 83.81 92.48 1.51 35.26 99.82 4.44 44.39 97.46 1.76 55.07 97.57 1.97 72.47 95.97 1.94
S23 Yes Med 38 13 96.13 76.30 0.59 70.19 97.07 2.68 50.55 97.69 1.51 64.98 97.71 1.71 79.93 95.95 1.65
S24 No Very 3 2 95.82 82.35 0.63 72.68 95.66 2.29 73.97 96.87 1.02 84.61 96.80 1.14 90.56 95.13 1.05
S25 No Low 90 33 84.45 91.58 1.41 38.40 99.82 4.20 43.23 97.30 1.76 53.61 97.40 1.92 70.81 95.85 1.90
S26 Yes Low 75 21 39.47 100.00 2.86 8.56 100.00 5.87 96.59 96.53 0.04 97.28 96.68 0.07 97.35 95.32 0.07
S27 Yes Very 150 27 39.12 100.00 2.83 7.25 100.00 5.82 93.24 97.44 0.18 95.85 96.74 0.23 96.37 94.52 0.21
S28 No Low 75 21 81.26 94.72 1.78 23.43 99.96 4.85 41.84 97.74 1.84 53.00 97.80 1.98 71.54 96.21 1.96
S29 No Med 150 27 57.36 99.10 2.75 1.72 100.00 5.93 41.77 98.09 1.71 54.86 98.18 1.92 73.44 96.57 1.90
S30 No Med 150 27 60.48 99.13 2.61 2.52 100.00 6.07 44.31 98.09 1.59 57.57 98.13 1.85 76.82 96.52 1.83
S31 Yes Low 150 27 43.27 100.00 2.84 9.41 100.00 5.91 95.65 97.72 0.13 97.30 97.80 0.16 97.38 96.31 0.14
S32 Yes Low 301 79 54.46 99.62 2.79 5.18 100.00 5.51 55.46 97.56 1.29 71.41 97.70 1.55 83.86 96.17 1.45
S33 Yes Med 30 6 83.53 98.05 1.75 24.05 99.85 4.68 59.93 98.22 1.34 76.47 98.19 1.55 87.59 96.45 1.43
S34 Yes Low 3 2 88.66 96.47 1.37 44.46 98.84 3.88 85.26 93.46 0.78 90.98 93.64 0.85 93.94 92.65 0.77
S35 No Very 6 4 92.46 86.87 0.99 61.42 98.47 3.17 53.22 96.79 1.55 66.86 96.84 1.68 79.88 95.28 1.62
S36 Yes Med 150 27 93.28 90.21 0.93 49.36 99.76 3.83 54.55 98.16 1.30 71.04 98.21 1.56 84.52 96.55 1.47
S37 Yes Low 3 2 97.15 64.58 0.45 81.88 85.24 1.67 46.60 96.01 1.75 54.49 96.11 1.86 69.87 94.60 1.86
S38 Yes Very 30 6 67.25 100.00 2.22 21.47 99.98 4.73 92.82 97.74 0.30 96.46 97.04 0.37 97.02 95.18 0.32
S39 Yes Med 3 2 93.60 90.28 0.97 60.27 98.51 3.06 68.82 95.82 1.18 79.02 95.89 1.28 87.15 94.46 1.21
S40 No Very 3 2 94.07 88.53 0.82 65.31 98.22 2.72 70.99 96.58 1.11 80.98 96.52 1.22 88.63 94.90 1.13
S41 No Med 3 2 94.43 87.00 0.82 64.58 97.88 2.86 64.91 96.00 1.26 75.00 96.08 1.40 85.45 94.58 1.35
S42 No Med 75 21 81.73 95.86 1.74 27.12 99.96 4.62 47.58 97.75 1.56 61.88 97.77 1.74 77.46 96.09 1.69
S43 No Very 75 21 85.26 96.00 1.54 35.59 99.89 4.24 53.46 97.76 1.42 68.39 97.75 1.62 82.17 95.93 1.53
S44 No Very 301 79 77.68 96.03 1.77 25.98 99.96 4.55 43.66 97.77 1.62 57.43 97.81 1.82 73.69 96.15 1.73
S45 No Med 38 13 84.90 92.79 1.49 36.94 99.83 4.30 45.06 97.50 1.75 56.52 97.60 1.91 73.64 96.03 1.83
S46 No Low 3 2 91.95 82.44 0.88 63.04 95.61 2.73 51.88 94.71 1.52 59.13 94.79 1.65 71.56 93.39 1.60
S47 Yes Med 75 21 85.95 92.50 1.43 35.59 99.88 4.39 44.91 97.82 1.69 57.02 97.87 1.94 74.66 96.25 1.91
S48 Yes Very 301 79 87.42 93.90 0.94 56.07 99.36 3.09 68.14 97.86 0.85 82.38 97.75 1.08 87.58 95.80 0.93
S49 Yes Med 1 6 93.90 85.16 0.71 71.25 97.17 2.32 71.01 93.88 0.85 79.66 93.88 0.95 86.39 92.79 0.94
S50 No Low 301 79 73.52 96.11 2.07 14.94 99.99 5.03 40.69 97.70 1.82 52.28 97.75 2.00 70.55 96.23 2.01
S51## No Low 90 33 NA 89.17 NA NA 99.92 NA NA 97.02 NA NA 97.06 NA NA 95.25 NA
S52## No Med 90 33 NA 95.65 NA NA 100.00 NA NA 96.97 NA NA 96.98 NA NA 95.15 NA
S53## No Very 38 13 NA 88.28 NA NA 99.70 NA NA 97.29 NA NA 97.03 NA NA 94.84 NA
S54## Yes Low 150 27 NA 98.29 NA NA 100.00 NA NA 97.87 NA NA 97.91 NA NA 96.07 NA
S55## Yes Med 301 79 NA 85.71 NA NA 99.88 NA NA 97.65 NA NA 97.65 NA NA 95.79 NA
S56## Yes Very 3 2 NA 75.16 NA NA 90.06 NA NA 96.52 NA NA 96.52 NA NA 94.28 NA

*The data set names identify the set of parameters used to generate the simulated data.
†A trend over the years was either included or not.
‡Seasonality was included at 3 levels. A dataset that is very seasonal might include pneumonia and influenza. Datasets with less seasonality are medium, and datasets in which we did not intentionally include any seasonality are low.
§The means and standard deviations (SD) used in the simulations were based on real means and SDs.
¶The seasonally adjusted CUSUM method sums the positive differences of the current value from the mean for a period similar to the current value over 5 years.
#The historical limits method compares the current sum of 4 periods to the mean of the sum of 15, 4 periods surrounding the current point of interest over 5 years.
**The C1-MILD method is based on CUSUM, but the calculations reduce to the current value being greater than the mean plus 3 SD, with the mean and standard deviation based on the past 7 days.
††The C2-MEDIUM method is based on CUSUM, but the calculations reduce to the current value being greater than the mean plus 3 SD, with the mean and SD based on the past 7 days shifted by 2 days.
‡‡The C3-ULTRA method is based on CUSUM, summing the positive difference of the current value form the mean for 3 days, with the mean and standard deviation based on the past 7 days shifted by 2 days.
§§95% confidence values were <0.06. Time to detection (ttd) must be interpreted with sensitivity because ttd does not include missed outbreaks.
##Datasets S51–S56 do not include any simulated outbreaks; therefore, sen and ttd cannot be calculated.

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