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86 lines
3.5 KiB
Plaintext
86 lines
3.5 KiB
Plaintext
10 months ago
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{smcl}
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{* 19nov2002}{...}
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{hline}
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help for {hi:leastlikely}{right:(SJ2-4: st0022_1)}
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{hline}
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{title:List least likely observations}
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{p 8 13}{cmd:leastlikely} [{it:varlist}] [{cmd:if} {it:exp}]
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[{cmd:in} {it:range}]
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[{cmd:,} {cmd:n(}{it:#}{cmd:)} {cmdab:g:enerate(}{it:varname}{cmd:)}
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[{cmdab:no:}]{cmdab:d:isplay} {cmdab:nol:abel} {cmdab:noo:bs}
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{cmdab:do:ublespace}]
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{title:Description}
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{p 4 4 2}For regression models for categorical dependent variables,
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{cmd:leastlikely} lists the in-sample observations with the lowest
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predicted probabilities of observing the outcome value that was
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actually observed. For example, in a model with a binary dependent
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variable, {cmd:leastlikely} lists the observations that have the lowest
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predicted probability of {it:depvar=0} among those cases for which
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{it:depvar=0}, and it lists the observations that have the lowest predicted
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probability of {it: depvar=1} among those cases for which {it:depvar=1}. The
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least likely values represent relatively deviant cases that may warrant
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closer inspection.
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{p 4 4 2}{cmd:leastlikely} works with estimation commands for models of binary
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outcomes in which option {cmd:p} after {cmd:predict} provides the predicted
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probability of a positive outcome (e.g., {cmd:logit}, {cmd:probit}), but the
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dependent variable must be coded as 0 and 1. Likewise, {cmd:leastlikely}
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works with estimation commands for models of ordinal or nominal outcomes
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in which option {cmd:outcome(}{it:#}{cmd:)} after {cmd: predict} provides the
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predicted probability of outcome {it:#}. Exceptions are commands in which the
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predicted probabilities are probabilities within groups or panels or for
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"blocked" data; {cmd:leastlikely} will produce an error message if executed
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after {cmd:blogit}, {cmd:bprobit}, {cmd:clogit}, {cmd:glogit},
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{cmd:gprobit}, {cmd:nlogit}, or {cmd:xtlogit}.
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{p 4 4 2}{cmd:leastlikely} lists the observation number and the
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predicted probability (as Prob or as the variable name specified by the
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{cmd:generate} option). Values of variables in {it:varlist} will also be
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specified.
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{title:Options}
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{p 4 8 2}{cmd:n(}{it:#}{cmd:)} specifies the number of observations to be listed
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for each outcome. The default is 5. If multiple observations have the same
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probabilities, more than the specified number will be listed to include all
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of them.
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{p 4 8 2}{cmd:generate(}{it:varname}{cmd:)} specifies that the probabilities
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of observing the outcome value that was observed should be stored in
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{it:varname}. If not specified, the variable name {cmd:Prob} will be created
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but dropped after the output is produced.
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{p 4 8 2}[{cmd:no}]{cmd:display} forces the format into {cmd:display} or
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tabular ({cmd:nodisplay}) format. If you do not specify one of these two
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options, then Stata chooses one based on its judgment of which would be most
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readable.
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{p 4 8 2}{cmd:nolabel} causes the numeric codes rather than the label values
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to be displayed.
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{p 4 8 2}{cmd:noobs} suppresses printing of the observation numbers.
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{p 4 8 2}{cmd:doublespace} produces a blank line between each observation in
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the listing when in {cmd:nodisplay} mode; it has no effect in {cmd:display}
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mode.
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{title:Examples}
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{p 4 8 2}{cmd:. logit low age lwt race2 race3 smoke ptl ht ui}{p_end}
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{p 4 8 2}{cmd:. leastlikely}{p_end}
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{p 4 8 2}{cmd:. leastlikely age lwt, n(10) g(prob)}{p_end}
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{title:Author}
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{browse "mailto:jfreese@ssc.wisc.edu":Jeremy Freese}
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Department of Sociology,
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University of Wisconsin-Madison
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