{smcl}
{* *! version 1.0 2/21/2018}
{title:Title}
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{cmd:gfi} {hline 2} defines and works with the formula for the structure of a designated focal variable’s interactive effect on the “modeled” outcome.
{title:Description}
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{cmd:gfi} produces algebraic expression for the effect of a focal variable as it changes with the moderators, a sign change analysis of the effect
and an optional visualization in a path-style diagram. Must run {help intspec} before running {cmd:gfi}. See Kaufman (2018)
for detailed explanation and step-by-step examples of using this and other ICALC add-on commands.
{title:Syntax}
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{cmd:gfi} {cmd:,} [ {opt fact:orchg} {opt ndig:its}(#) {opt path}({opt type} , {opt ti:tle}({it:string}) {opt name}({it:string})
{opt boxw:idth}(#) {opt ygap}(#) {opt xgap}(#) {opt ndig:its}(#) ) ]
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{p2col: {it:options}}Description {p_end}
{hline}
{p2col:{cmd:factorchg}}algebraic expression for moderated effect of focal variable also shown as a factor change if this keyword is specified
{p2col:{cmd:ndigits(#)}}number of digits after decimal for effects and coefficients in algebraic expression and sign change table. {bf:Default = 4}.
{p2col:{cmd:path(type, suboptions)}}Create path diagram of structure of interaction effect
{p_end}
{p2colset 7 23 23 2}
{p2col:{it:type}}{it:focal} or {it:all}. {it:focal} shows only coefficient values for variables involving focal variable.
{it:all} shows all coefficient values. {bf:Default is focal}.
{p_end}
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{p2col:{it:suboptions}}{cmd:title({it:string})} {it:string} is title for path diagram {p_end}
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{cmd:name({it:string}}) save as memory graph with name given by {it:string} {p_end}
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{cmd:ndigits(#)} # of digits used to report coefficient values in diagram {p_end}
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{cmd:boxwidth(#)}, {cmd:ygap(#)}, {cmd:xgap(#)} use to fine-tune graph. boxwidth sets width of boxes;
ygap sets vertical distance between boxes; xgap sets horizontal distance between boxes. {bf:Defaults are boxwidth(1.25), ygap(.625), xgap(1.25)}.
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{bf:Note:} Moderator {cmd:range( )} specifications define points at which moderated effect is calculated in sign change analysis.
For categorical variables all categories define calculation points.
{title:Example: two-way interaction}
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For a model predicting poor mental health days ({it:pmhdays}) by the interaction of work-family conflict ({it:wfconflict}) and job status ({it:sei}), {cmd:intspec}
specfies {it:wfconflict} as the focal variable and {it:sei} as its moderator. {cmd:gfi} produces the formula for how Job STatus ({it:sei}) moderates the effect of
Work Famly Conlict ({it:wfconflict}) on {it:pmhdays} and a table portraying when, if at all, the moderated effect of {it:wfconflict} changes sign.
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nbreg pmhdays c.wfconflict##c.sei ... {p_end}
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intspec, focal(c.wfconlifct) main( (c.sei name(JobStatus) range(17(10)97)) (c.wfconflict name(WorkFamConflict) range(1/4))) int2vars(c.wfconflict#c.sei) {p_end}
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gfi , ndigits(5)
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*** Also show formula for moderated effect of wfconflict as a factor change
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gfi , ndigits(5) factorchg
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*** Also draw path-style diagram of the effect of wfconflict moderated by sei
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gfi , ndigits(5) factorchg path(all)
{title:Author and Citation}
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I would appreciate users of this and other ICALC commands citing
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Robert L. Kaufman. 2018. {it: Interaction Effects in Linear and Generalized Linear Models}, Sage Publcations.