Table 2

Estimated power, sensitivity and positive predictive value (PPV) when the normal scan statistic is used to detect different types of clusters, as described in the text.

Cluster number

Cluster size (%)

Sample size

Cluster mean

Cluster STD

Power (%)

Sensitivity

PPV

Different Cluster Locations

1

10

600

-10%

600

66

0.70

0.74

2

10

600

-10%

600

54

0.56

0.65

3

10

600

-10%

600

64

0.72

0.82

4

10

600

-10%

600

61

0.61

0.64

Different Cluster Size

1

5

600

-10%

600

34

0.52

0.48

1

10

600

-10%

600

66

0.70

0.74

1

20

600

-10%

600

96

0.87

0.89

Different Sample Size

1

10

300

-10%

600

34

0.55

0.56

1

10

600

-10%

600

66

0.70

0.74

1

10

900

-10%

600

89

0.83

0.82

1

10

1200

-10%

600

98

0.85

0.85

Different Mean Weight Reduction

1

10

600

-5%

600

14

0.30

0.38

1

10

600

-8%

600

42

0.56

0.61

1

10

600

-10%

600

66

0.70

0.74

1

10

600

-13%

600

92

0.84

0.84

1

10

600

-15%

600

98

0.88

0.88

1

10

600

-20%

600

100

0.93

0.93

Different Standard Deviation

1

10

600

-10%

300

100

0.93

0.93

1

10

600

-10%

600

66

0.70

0.74

1

10

600

-10%

900

28

0.45

0.51

Kulldorff et al. International Journal of Health Geographics 2009 8:58   doi:10.1186/1476-072X-8-58