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help for ^rfprobit^ (STB-26: sg41)
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Random-effects probit
---------------------
^rfprobit^ depvar [indepvars] [^if^ exp] [^in^ range] ^,^ [ ^i(^varname^)^
^q^uadrat^(^#^)^ ^nochi^sq ^nolo^g ^l^evel^(^#^)^ maximize_options ]
This command shares the features of all estimation commands; see help @est@.
To reset problem-size limits, see help @matsize@.
Description
-----------
^rfprobit^ estimates a random-effects probit model for cross-sectional time-
series data sets using maximum likelihood estimation. The likelihood (for
an independent unit i) is expressed as an integral which is computed using
Gaussian-Hermite quadrature. This computational procedure is only accurate
when there are a small-to-moderate number of time periods T_i per unit i.
It is recommended that ^rfprobit^ only be used when max(T_i) <= 50.
Options
-------
^i(^varname^)^ specifies the variable corresponding to an independent unit
(e.g., a subject id). This variable represents the i in x_it. Either
this option must be specified or i must be set using the ^iis^ command;
see help for @xt@.
^quadrat(^#^)^ specifies the number of points to use for Gaussian-Hermite
quadrature. Default is 6. Increasing this value slightly improves
accuracy, but also increases computation time. Computation time is
roughly proportional to its value.
^nochisq^ omits the estimation of the constant-only model. This will reduce
computation time at the cost of not being able to calculate the model
chi-squared or pseudo R^^2.
^nolog^ suppress the display of the likelihood iterations.
^level(^#^)^ specifies the significance level, in percent, for confidence
intervals of the coefficients; see help @level@.
maximize_options control the maximization process; see [7] maximize.
Use the ^trace^ option to view parameter convergence.
The ^ltol(^#^)^ option can be used to loosen the convergence
criterion (default is 1e-6) during specification searches.
Examples
--------
. ^rfprobit y x, i(id)^
. ^iis id^
. ^rfprobit y x^
. ^rfprobit y x, i(id) nochisq^
. ^rfprobit y x, i(id) quad(8) nolog^
. ^rfprobit y x, i(id) trace^
. ^rfprobit^
Method
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^rfprobit^ uses the deriv1 method (analytic first derviatives) of Stata's ^ml^
commands. See Butler and Moffitt (1982) for details.
Author
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Bill Sribney
Stata Corporation
702 University Drive East
College Station, TX 77840
Phone: 409-696-4600
800-782-8272
Fax: 409-696-4601
email: tech_support@@stata.com
Reference
---------
Butler, J.S. and R. Moffitt. 1982. A computationally efficient quadrature
procedure for the one-factor multinomial probit model. Econometrica 50:
761-764.
Also see
--------
STB: STB-26 sg41
Manual: [5s] xt, [5s] xtreg, [7] maximize
On-line: help for @xt@, @xtreg@