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82 lines
2.3 KiB
Plaintext
82 lines
2.3 KiB
Plaintext
9 months ago
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help for ^eq^
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Define and list equations
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-------------------------
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^eq^ [^define^] eqtn
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^eq^ [^define^] eqname ^:^ [eqtn]
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^eq dir^ [^_all^ | eqname [eqname ..]]
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^eq list^ [^_all^ | eqname [eqname ..]]
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^eq drop^ {^_all^ | eqname [eqname ..]}
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Description
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-----------
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^eq define^ is used to define equations in ^gllamm^. In Stata 5 and earlier this
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was also used by Stata's own multivariate estimation commands. The command
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continues to work in Stata 8 but is no longer documented.
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^eq dir^ and ^eq list^ are used to review equations that
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have been defined. ^eq drop^ is used to eliminate previously defined equations.
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^gllamm^ has options ^eqs(eqnames)^ ^geqs(eqnames)^ ^peqs(eqname)^ and ^s(eqname)^
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where eqnames is a list of equation names and eqname is an equation name.
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You first define equations using ^eq^ and then estimate the model.
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Equations are named and usually define a variable list. For instance,
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to estimate a factor model in ^gllamm^, an equation of the following
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kind must be defined:
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. ^eq load: d1 d2 d3^
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where d1, d2 and d3 are dummy variables for three variables or items
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loading on one of the factors. You can abbreviate variable names and
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take all the other shortcuts you would when specifying a varlist in a
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command:
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. ^eq load: d1-d3^
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When you do not specify the equation name followed by a colon, the first name
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is taken both as the equation name and as part of the contents of the equation.
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There is one exception to this rule. You may not type
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. ^eq price^
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You must type instead
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. ^eq price: price^
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(Such nearly empty equations are not silly; it could mean that price is to
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be estimated by an intercept-only equation.) One can also define completely
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empty equations in this way:
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. ^eq price: ^
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Note the distinction: "^eq price: price^" defines equation price to contain
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"price"; "^eq price:^" defines price to contain nothing.
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Equations can be dropped,
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. ^eq drop load^
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. ^eq load: d1 d2 d3^
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or you can redefine equations without bothering to drop them first.
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Equations may be listed for review:
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. ^eq list load^
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. ^eq list load1 load2^
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. ^eq list^
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You can list just the equation names using ^eq dir^:
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. ^eq dir^
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