Table 2

Estimated annual incidence and Weibull parameters for major depression

Year

N

Approximate incidence proportion*

Model-Based Estimates

Approximate Incidence Proportion*

Adjusted Annual Incidence**

Weibull Scale Parameter

Weibull Shape Parameter

1994–96

9370

3.5%

3.5%

2.8%

52.9

0.66

1996–98

9689

3.6%

3.6%

2.8%

52.9

0.66

1998–00

9427

3.8%

3.8%

3.1%

47.4

0.71

2000–02

9244

3.8%

3.8%

3.1%

47.9

0.86

* proportion without an episode in the year preceding the start of the interval (1994, 1996, 1998 or 2000) who have an episode in the year preceding the following interview.

** using the exponential formula (2 year incidence = 1 - e^{-one year rate*2}) these annual rates correspond to predicted 2-year incidence ranging from 5.4% to 6.0%.

Patten Clinical Practice and Epidemiology in Mental Health 2006 2:13   doi:10.1186/1745-0179-2-13