▁trade ▁flows ▁to ▁and ▁from ▁a ▁region . ▁As ▁an ▁alternative , ▁the ▁concepts ▁of ▁basic ▁and ▁non basic ▁are ▁oper ational ized ▁using ▁employ ment ▁data . ▁The ▁theory ▁was ▁developed ▁by ▁Robert ▁Murray ▁Ha ig ▁in ▁his ▁work ▁on ▁the ▁Regional ▁Plan ▁of ▁New ▁York ▁in ▁ 1 9 2 8 . ▁ ▁The ▁basic ▁indust ries ▁of ▁a ▁region ▁are ▁identified ▁by ▁comparing ▁employ ment ▁in ▁the ▁region ▁to ▁national ▁norm s . ▁If ▁the ▁national ▁norm ▁for ▁employ ment ▁in , ▁for ▁example , ▁Egypt ian ▁wood wind ▁manufact uring ▁is ▁ 5 ▁percent ▁and ▁the ▁region ' s ▁employ ment ▁is ▁ 8 ▁percent , ▁then ▁ 3 ▁percent ▁of ▁the ▁region ' s ▁wood wind ▁employ ment ▁is ▁basic . ▁Once ▁basic ▁employ ment ▁is ▁identified , ▁the ▁out look ▁for ▁basic ▁employ ment ▁is ▁investig ated ▁sector ▁by ▁sector ▁and ▁pro jections ▁made ▁sector ▁by ▁sector . ▁In ▁turn , ▁this ▁perm its ▁the ▁projection ▁of ▁total ▁employ ment ▁in ▁the ▁region . ▁Typ ically ▁the ▁basic / non basic ▁employ ment ▁ratio ▁is ▁about ▁ 1 : 1 . ▁Ext ending ▁by ▁manip ulation ▁of ▁data ▁and ▁compar isons , ▁conject ures ▁may ▁be ▁made ▁about ▁population ▁and ▁income . ▁This ▁is ▁a ▁rough , ▁service able ▁procedure , ▁and ▁it ▁remains ▁in ▁use ▁today . ▁It ▁has ▁the ▁advantage ▁of ▁being ▁readily ▁oper ational ized , ▁f idd led ▁with , ▁and ▁understand able . ▁▁ ▁The ▁formula ▁for ▁computing ▁location ▁quot ients ▁can