NOTES ON R78A2BD.DAT:

     This dataset contains the variables (in this order):
     AGE2 YEAR POSB POSC POS NEGD NEGC NEG EMPSH

     AGE2=plant age category, a code which is either 0, 1, 2, 3,
4, 6, 11, or 15. AGE2 is defined only for the years which are the
last  year of an ASM panel (1978, 1983, 1988), becuase this
allows the longest, most precise age classification. The precise
definition of the category is as follows:

     AGE itself is measured as the difference between the first
year the establishment was ever observed in the dataset and the
current year. Thus, if the first year the establishment was ever
observed in the dataset is defined as frstyear, then 
     AGE = (year-frstyear).

  if .<AGE<1 then AGE2=0
  if 1<=AGE<2 then AGE2=1
  if 2<=AGE<3 then AGE2=2
  if 3<=AGE<4 then AGE2=3
  if 4<=AGE<6 then AGE2=4
  if 6<=AGE<11 then AGE2=6
  if 11<=AGE<15 then AGE2=11
  if 15<=AGE then AGE2=15
    


     YEAR= 1978
(note: year 78 refers to the changes from March 77 to March 78)

     POSB= annual job creation from establishments starting up

     POSC= annual job creation from continuing (already
     existing) establishments

     POS= annual job creation for both startups
     and continuing establishments

     NEGD= annual job destruction from establishments shutting
down

     NEGC= annual job destruction from continuing (already
     existing) establishments

     NEG= annual job destruction for both shutdowns and
continuing establishments

     EMPSH= employment share for each age class. It is:

     empsh=emp(i,t)/emp(t), 

     where emp(i,t) is the employment measure  used in the Davis-
     Haltiwanger work (specifically, average employment over two
     years for age class i in year t and emp(t) is the Davis
     Haltiwanger employment measure (again, the average  of
     employment over two years) across all age classes for year t 

Note further:

POS = POSB + POSC
NEG = NEGD + NEGD


(all measures are expressed as percentages)
(all measures are expressed as rates relative to the emp measure)