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Help on indicator variables

I would use a logical variable, with values TRUE and FALSE, instead
of a numeric indicator.  E.g., I find the following easier to follow
    bL <- ABS==1 | DEFF==1
    if (any(bL)) { do.this() }
than
    bN <- ifelse(ABS == 1 | DEFF == 1, 1, 0)
    if (any(bN == 1)) { do.this() }
The latter leaves me wondering what other values bN might have;
the former makes it clear this is a TRUE/FALSE dichotomy.

Logicals get converted to numbers (FALSE->0, TRUE->1) when used in
arithmetic so you can do, e.g., mean(bL) to see what proportion of
your cases satisfy the condition.

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com