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Title stata.com constraint — Define and list constraints SyntaxMenuDescriptionRemarks and examples ReferencesAlso see Syn
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stata.com constraint — Define and list constraints Syntax References
Menu Also see
Description
Remarks and examples
Syntax Define constraints constraint define # exp=exp | coeflist List constraints constraint dir
constraint list
numlist | all
numlist | all
Drop constraints constraint drop
numlist | all
Programmer’s commands constraint get # constraint free where coeflist is as defined in [R] test and # is restricted to the range 1–1,999, inclusive.
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Manage constraints
Description constraint defines, lists, and drops linear constraints. Constraints are for use by models that allow constrained estimation. Constraints are defined by the constraint command. The currently defined constraints can be listed by either constraint list or constraint dir; both do the same thing. Existing constraints can be eliminated by constraint drop. constraint get and constraint free are programmer’s commands. constraint get returns the contents of the specified constraint in macro r(contents) and returns in scalar r(defined) 0 or 1—1 being returned if the constraint was defined. constraint free returns the number of a free (unused) constraint in macro r(free). 1
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constraint — Define and list constraints
Remarks and examples
stata.com
Using constraints is discussed in [R] cnsreg, [R] mlogit, and [R] reg3; this entry is concerned only with practical aspects of defining and manipulating constraints.
Example 1 Constraints are numbered from 1 to 1,999, and we assign the number when we define the constraint: . use http://www.stata-press.com/data/r13/sysdsn1 (Health insurance data) . constraint 2 [indemnity]2.site = 0
The currently defined constraints can be listed by constraint list: . constraint list 2: [indemnity]2.site = 0
constraint drop drops constraints: . constraint drop 2 . constraint list
The empty list after constraint list indicates that no constraints are defined. Below we demonstrate the various syntaxes allowed by constraint: . constraint 1 [Indemnity] . constraint 10 [Indemnity]: 1.site 2.site . constraint 11 [Indemnity]: 3.site . constraint 21 [Prepaid=Uninsure]: nonwhite . constraint 30 [Prepaid] . constraint 31 [Insure] . constraint list 1: [Indemnity] 10: [Indemnity]: 1.site 2.site 11: [Indemnity]: 3.site 21: [Prepaid=Uninsure]: nonwhite 30: [Prepaid] 31: [Insure] . constraint drop 21-25, 31 . constraint list 1: [Indemnity] 10: [Indemnity]: 1.site 2.site 11: [Indemnity]: 3.site 30: [Prepaid] . constraint drop _all . constraint list
Technical note The constraint command does not check the syntax of the constraint itself because a constraint can be interpreted only in the context of a model. Thus constraint is willing to define constraints that later will not make sense. Any errors in the constraints will be detected and mentioned at the time of estimation.
constraint — Define and list constraints
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References Buis, M. L. 2012. Stata tip 108: On adding and constraining. Stata Journal 12: 342–344. Weesie, J. 1999. sg100: Two-stage linear constrained estimation. Stata Technical Bulletin 47: 24–30. Reprinted in Stata Technical Bulletin Reprints, vol. 8, pp. 217–225. College Station, TX: Stata Press.
Also see [R] cnsreg — Constrained linear regression