SEMAINE D’ETUDE SUR LE ROLE DE L’ANALYSE ECONOMETRIQUE ETC. 121 
It will suffice for our purpose to consider relationships and 
eo ipso predictors that are linear. The following terms and 
notations will be used throughout: 
(3) 
>= (Vie Vopp 
A 
“I 
is the vector of current endogenous variables: 
(4) 
<= (X1p Xap -- 
Xomt 
is the vector of exogenous variables: and 
(5) 
2,=(V, 1s Vas ee) 5 
is the vector of predetermined variables. 
(.X1. Vector repression (VR-) systems 
The general formula for linear vector regression is given . 
'6) y, = Li(V,_15 Vio ori Xu Xo qs ...) FV; 
where 1=1 ..., n; the functions L; are linear; and we assume 
that L. is an eo ipso predictor of v., for all : and £, 
(7) 
E(ly._1 Yi 
L;y,_.. 
In matrix representation we write the vector regression 
system (6)-(7) as follows, 
‘8 
Mg 
+ 
4 4 
‘21 Wold - pag. 7