1405-3195 1405-3195 S1405-31952007000400425 Mexico Mexico Mexico Mexico 00 06 2007 00 06 2007 41 4 425 433

1988 33 121-9 2003 26 1 1 11-7 1978 18 533-6 1994 39 213-8 2000 112 145-50 1989 9 207-12 1985 25 819-21 1980 25 135-47 1981 17 195-201 1983 38 327-38 1988 11 103-20 1956 9 463-93 1988 Second 468 1979 15 73-9 1994 22 461-6 1976 16 230-3 1978 27 27-32 1979 19 239-42 1988 33 37-49 1999 39 654-8 2004 27 1 1 49-56 1998 103 259-63 SAS Institute Inc. 1989 4 2003 1-19