Output   I      II     III      IV       V      VI
  1     214     696    3202    5668    6000   11796
  2     419     811    4802    7612    8222   15551
  3     588    1640    5821   10206    8484   27218
  4    1025    2506    9275   13702   10004   30958
/*
Data Description:
  Panel data  of output in millions of kilowatt-hours for six firms
  (I, II, III, IV, V, IV) in four time periods (1, 2, 3, 4)
Data Source:
  W. Greene, "Simutaneous Estimation of Factor Subsititution, 
  Economies of Scale, and Non-Neutral Technical Change," in 
  A. Dogramaci, ed. Econometric Analyses of Productivity,
  Kluwer-Nijoff, Boston, 1983. Also see W. Greene [1997], 
  Chap. 14, p. 614.
*/