Description Usage Arguments Details Value Author(s)
ncc_eligible_controls
calculates the number of eligible controls for each
case for a nested case control study. Given time of entry, time of exit, and
exit status,
risk sets are computed at each failure time. If matching variables are specified,
ncc_eligible_controls
creates matched or stratified risk sets,
which are computed separately within matching strata.
1 2 |
entry |
time of entry to follow-up |
exit |
time of exit from follow-up |
fail |
indicator of status on exit from follow-up (censored=0, fail=1) |
origin |
the origin of the analysis time-scale. For instance, date of birth, if age is the desired time-scale. |
match |
a list of categorical variables for matching cases and controls |
include |
a list of variables to include in the returned data.frame |
data |
a |
silent |
if |
Given follow-up information from a cohort study, ncc_eligible controls
generates
risk sets at each observed failure time, and counts the number of eligible
controls within each risk set. This information can be used to calculate the
probability of inclusion in the NCC study (see ncc_selection_prob
)
A data.frame
comprising:
ncc_id |
a unique individual identifier |
ncc_elig_co |
a count of the number of controls eligible for selection in the set |
followed by the variables specified in the match
and include
lists.
David C Muller
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