Create the RAM specification of a structural equation model.
1 2 3 4  specify.model(file = "")
## S3 method for class 'mod'
print(x, ...)

file 
The (quoted) file from which to read the model specification,
including the path to the file if it is not in the current directory. If

x 
An object of class 
... 
Ignored. 
Each line of the RAM specification consists of three (unquoted) entries, separated by commas:
This is a simple formula, of the form
A > B
or, equivalently, B < A
for a regression
coefficient (i.e., a singleheaded or directional arrow);
A <> A
for a variance or A <> B
for a covariance
(i.e., a doubleheaded or bidirectional arrow). Here, A
and
B
are variable names in the model. If a name does not correspond
to an observed variable, then it is assumed to be a latent variable.
Spaces can appear freely in an arrow specification, and
there can be any number of hyphens in the arrows, including zero: Thus,
e.g., A>B
, A > B
, and A>B
are all legitimate
and equivalent.
The name of the regression coefficient, variance,
or covariance specified by the arrow. Assigning the same name to two or
more arrows results in an equality constraint. Specifying the parameter name
as NA
produces a fixed parameter.
start value for a free parameter or value of a fixed parameter.
If given as NA
, sem
will compute the start value.
Lines may end in a comment following \#
.
See sem
for further details on model specification.
An object of class mod
, suitable as input for sem
.
John Fox jfox@mcmaster.ca
sem
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27  ## Not run:
model.dhp < specify.model()
RParAsp > RGenAsp, gam11, NA
RIQ > RGenAsp, gam12, NA
RSES > RGenAsp, gam13, NA
FSES > RGenAsp, gam14, NA
RSES > FGenAsp, gam23, NA
FSES > FGenAsp, gam24, NA
FIQ > FGenAsp, gam25, NA
FParAsp > FGenAsp, gam26, NA
FGenAsp > RGenAsp, beta12, NA
RGenAsp > FGenAsp, beta21, NA
RGenAsp > ROccAsp, NA, 1
RGenAsp > REdAsp, lam21, NA
FGenAsp > FOccAsp, NA, 1
FGenAsp > FEdAsp, lam42, NA
RGenAsp <> RGenAsp, ps11, NA
FGenAsp <> FGenAsp, ps22, NA
RGenAsp <> FGenAsp, ps12, NA
ROccAsp <> ROccAsp, theta1, NA
REdAsp <> REdAsp, theta2, NA
FOccAsp <> FOccAsp, theta3, NA
FEdAsp <> FEdAsp, theta4, NA
model.dhp
## End(Not run)

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