Gives each named item a separate location in every frame in which it was administered, then refits the EFRM.
Arguments
- fit
A fitted object from
rasch_efrm.- items
Item names to resolve.
- boot_reps
Bootstrap replicates for the refit. The default retains the fitted specification; a number overrides it.
Value
A refitted object of class "rasch_efrm", carrying a note
for each item resolved. The resolved versions appear in the item table
as "item (frame)".
Details
A resolved item continues to contribute to person measurement within each
frame but no longer constrains the link between those frames. Its versions
are named "item (frame)". The remaining common items and the linked
set design must still identify the frame units; otherwise the refit is
refused by the model's connectivity and rank checks.
Each set must also retain links between its groups of item versions to
identify their relative origins. A unit link supplied by another set
cannot replace these origin links.
Resolve an item when its within-frame measurement remains defensible but
its cross-frame location does not. This refit does not estimate a separate
discrimination and therefore does not resolve a discrimination-only flag
from frame_invariance. Review or remove such an item instead.
Use drop_items when the item should no longer contribute to
measurement. Each resolved version must observe every score category of the
source item. If it does not, the refit is refused rather than renumbering
that frame's scores.
See also
frame_invariance, which identifies the items to
resolve; drop_items, which removes an item instead; and
split_items, the equivalent for an ordinary fit.
Examples
d <- simulate_efrm(n_per_group = 200, items_per_set = 6, n_sets = 2,
n_groups = 2, set_unit_ratio = 1.3, seed = 5)
tr <- attr(d, "truth")
fit <- rasch_efrm(d, item_sets = tr$item_sets, groups = "group",
id = "id", boot_reps = 0)
fit2 <- resolve_frames(fit, "S1I02", boot_reps = 0)
grep("S1I02", fit2$items$item, value = TRUE)
#> [1] "S1I02 (g1):g1" "S1I02 (g2):g2"