▁That ' s ▁going ▁to ▁hit ▁the ▁economy ▁hard ▁because ▁it ▁means ▁a ▁loss ▁of ▁ 1 0 , 0 0 0 ▁jobs ▁in ▁the ▁community ." ▁ ▁To ▁forec ast , ▁the ▁main ▁procedure ▁is ▁to ▁compare ▁the ▁region ▁with ▁the ▁nation ▁and ▁national ▁tr ends . ▁If ▁the ▁economic ▁base ▁of ▁a ▁region ▁is ▁in ▁indust ries ▁that ▁are ▁decl ining ▁nation wide , ▁then ▁the ▁region ▁faces ▁a ▁problem . ▁If ▁its ▁economic ▁base ▁is ▁concentr ated ▁in ▁se ctors ▁that ▁are ▁growing , ▁then ▁it ▁is ▁in ▁good ▁shape . ▁ ▁Method olog ically , ▁economic ▁base ▁analysis ▁views ▁the ▁region ▁as ▁if ▁it ▁were ▁a ▁small ▁nation ▁and ▁uses ▁not ions ▁of ▁relative ▁and ▁compar ative ▁advantage ▁from ▁international ▁trade ▁theory ▁( Char les ▁T ieb out ▁ 1 9 6 3 ). ▁In ▁a ▁sense , ▁the ▁activity ▁is ▁macro e conom ics ▁" written ▁small ", ▁and ▁it ▁has ▁not ▁been ▁of ▁much ▁interest ▁to ▁urban ▁econom ists ▁in ▁recent ▁years ▁because ▁it ▁does ▁not ▁get ▁at ▁within - city ▁relationships . ▁The ▁analysis ▁usually ▁takes ▁US ▁growth ▁patterns ▁as ▁a ▁given . ▁The ▁f ates ▁of ▁regions ▁are ▁determined ▁by ▁tr ends ▁in ▁the ▁national ▁economy . ▁ ▁Ass um ptions ▁ ▁As ▁H . ▁Craig ▁Davis ▁points ▁out , ▁there ▁are ▁a ▁number ▁of ▁assumptions ▁on ▁which ▁economic ▁base ▁analysis ▁is ▁conducted . ▁These ▁include ▁( 1 ) ▁that ▁exports ▁are ▁the ▁sole ▁source ▁of ▁economic ▁growth ▁( in vest ment , ▁government ▁sp