s , ▁Try g ve ▁Ha avel mo ▁published ▁The ▁Pro b ability ▁Appro ach ▁in ▁E con omet rics ▁in ▁ 1 9 4 4 , ▁where ▁he ▁assert ed ▁that ▁precise ▁statistical ▁analysis ▁could ▁be ▁used ▁as ▁a ▁tool ▁to ▁validate ▁mathematical ▁theories ▁about ▁economic ▁actors ▁with ▁data ▁from ▁complex ▁sources . ▁ ▁This ▁linking ▁of ▁statistical ▁analysis ▁of ▁systems ▁to ▁economic ▁theory ▁was ▁also ▁prom ul g ated ▁by ▁the ▁Cow les ▁Commission ▁( now ▁the ▁Cow les ▁Foundation ) ▁throughout ▁the ▁ 1 9 3 0 s ▁and ▁ 1 9 4 0 s . ▁ ▁The ▁roots ▁of ▁modern ▁econ omet rics ▁can ▁be ▁trac ed ▁to ▁the ▁American ▁econom ist ▁Henry ▁L . ▁Moore . ▁ ▁Moore ▁studied ▁agricult ural ▁product ivity ▁and ▁attempted ▁to ▁fit ▁changing ▁values ▁of ▁product ivity ▁for ▁plots ▁of ▁corn ▁and ▁other ▁cro ps ▁to ▁a ▁curve ▁using ▁different ▁values ▁of ▁el astic ity . ▁ ▁Moore ▁made ▁several ▁errors ▁in ▁his ▁work , ▁some ▁from ▁his ▁choice ▁of ▁models ▁and ▁some ▁from ▁limitations ▁in ▁his ▁use ▁of ▁mathematics . ▁ ▁The ▁accuracy ▁of ▁Moore ' s ▁models ▁also ▁was ▁limited ▁by ▁the ▁poor ▁data ▁for ▁national ▁accounts ▁in ▁the ▁United ▁States ▁at ▁the ▁time . ▁ ▁While ▁his ▁first ▁models ▁of ▁production ▁were ▁static , ▁in ▁ 1 9 2 5 ▁he ▁published ▁a ▁dynamic ▁" mov ing ▁equilibrium " ▁model ▁designed ▁to ▁explain ▁business ▁cycles — this ▁periodic ▁variation ▁from ▁over - cor re ction ▁in ▁supply ▁and ▁demand ▁curves