Factor Analysis and Principal Components Analysis 239
where=
Y
yyyyyyNtNtTNT11 111is the matrix of the data, in which every row corresponds to an observa-
tion of all N variables, and each column corresponds to all T observa-
tions of each variable; and where=
F
ffffff1
1
1
qtqtTqT11 111is the matrix of factors where we add a column of ones to include the
constant terms a (note that the terms of this matrix are not observable)=
C
aa
bbbbN
NqNq1
11 11is the matrix of factor loadings plus the terms a in the first row.=
εεεεεε
E
NtNtTNT11 111is the matrix of error terms, which are not observable.