Data frame:vlbw

671 observations and 26 variables, maximum # NAs:381

Name	Labels	Units	Levels	Storage	NAs
birth	date of birth (admission)			double	21
exit	date of death or discharge			double	31
hospstay	hospstay			double	31
lowph	lowest pH in first 4 days of life			double	62
pltct	platelet count			double	70
race			4	integer	25
bwt	birth weight	g		double	2
gest	gestational age	weeks		double	4
inout			2	integer	3
twn	multiple gestation			double	20
lol	duration of labor	h		double	381
magsulf	mother treated with MgSO4			double	247
meth	mother treated with beta-methasone			double	106
toc	tocolysis - mother treated with beta-adrenergic drug			double	106
delivery			2	integer	22
apg1	apgar at one minute			double	34
vent	assisted ventilation used			double	30
pneumo	pneumothorax occurred			double	26
pda	patent ductus arteriosus detected			double	29
cld	on suppl. oxygen at 30 days			double	66
pvh			3	integer	145
ivh			3	integer	144
ipe			3	integer	144
year	Year of birth (+ fraction)			double	21
sex			2	integer	21
dead				double	0