[R-sig-Epi] Nested case-control, multiple matching factors

[Albert V. Smith]

I would like to generated a nested case-control set, using multiple
factors to match. I am using the ‚ccwc‘ function, and while I apparently
get the right behavior, I end up with a combo of misnamed and unnamed
columns. I am unsure whether this is a bug, or whether I am making an
inappropriate call.

Example:

-----

suppressMessages(library(Epi))
data(diet)

# Example from the Documentation

suppressWarnings(head(ccwc(doe, dox, chd, origin = dob, controls = 2, data
= diet,
    include = energy, match = job)))

##
## Sampling risk sets: .............................................

##   Set Map       Time Fail       job energy
## 1   1   3 1984-03-20    1 Conductor  24.95
## 2   1 230 1982-03-14    0 Conductor  36.18
## 3   1  46 1978-10-08    0 Conductor  22.37
## 4   2   9 1976-07-27    1 Conductor  23.16
## 5   2 166 1981-12-09    0 Conductor  27.03
## 6   2 253 1973-05-13    0 Conductor  32.71

# Exactly as it should, given this is the example from the documentation

# Then..., trying matching on multiple factors.

# Matching on multiple factors results in mislabeled columns, as well as
# unlabeled columns

suppressWarnings(head(ccwc(doe, dox, chd, origin = dob, controls = 2, data
= diet,
    include = list(height, weight, fat), match = list(job, energy.grp))))

##
## Sampling risk sets: ..............................................

##   Set Map       Time Fail    height       weight   fat   NA.  NA..1
## 1   1   3 1984-03-20    1 Conductor <=2750 KCals 152.4 49.90 11.249
## 2   1  70 1978-06-01    0 Conductor <=2750 KCals 170.2 67.59 10.702
## 3   1 149 1983-11-03    0 Conductor <=2750 KCals 170.0 59.51 10.798
## 4   2   9 1976-07-27    1 Conductor <=2750 KCals 174.0 66.00 10.140
## 5   2 187 1972-04-05    0 Conductor <=2750 KCals 172.7 71.90 10.019
## 6   2  13 1972-03-23    0 Conductor <=2750 KCals 174.0 61.46  7.272


-----

I am ending up with the the retained columns at the end, as well as the
columns used for matching. However, the names for the included columns are
not assigned properly, and there while the names for the matched columns
are not retained.

Is this a bug, or am I making an inappropriate call to the ‚ccwc‘ function?

Thanks,
-albert












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