Figure 1From: Increasing illness severity in very low birth weight infants over a 9-year periodStandardized rate for death and/or severe IVH. Standardized rate is a ratio of observed/expected rate of death and/or severe IVH. Expected rate of IVH was calculated using logistic regression models (see text) using either SNAP or T4 to adjust for illness severity. Checkered box indicates 1993–1996, black boxes 1996–1999, white boxes 1999–2002.Back to article page