document formula convention and bump

Author: philchalmers

DESCRIPTION

@@ -1,5 +1,5 @@
 Package: mirt
-Version: 1.42.4
+Version: 1.42.5
 Type: Package
 Title: Multidimensional Item Response Theory
 Authors@R: c( person("Phil", family="Chalmers", email =

NEWS.md

@@ -2,7 +2,8 @@
 
 - Related to both points below, general MLTM (Embretson, 1984) added when 
   itemtype is specified as `PC1PL` and an `itemdesign` set is used, where 
-  formula must include name of the factor in the formula expressions
+  formula must include the name of the factor in the formula expressions. See
+  examples in the `mirt` documentation (requested by Susan Embretson)
 
 - Added `PC1PL` itemtype to more easily specify conjunctive models with
   slopes fixed to 1 and estimation of the latent variance term, mimicking the 
@@ -17,7 +18,7 @@
   when loading structures specified where trace lines products are only 
   computed for dimensions with non-zero slopes
 
-- `RCI()` gains a `shiny` logical create an interactive scoring interface
+- `RCI()` gains a `shiny` logical to create an interactive scoring interface
 
 # Changes in mirt 1.42
 

R/mirt.R

@@ -484,7 +484,12 @@
 #'   \code{item.formula}. Providing this input will fix the associated \code{'d'} intercepts
 #'   to 0, where applicable
 #' @param item.formula an R formula used to specify any intercept decomposition (e.g.,
-#'   the LLTM; Fischer, 1983)
+#'   the LLTM; Fischer, 1983). Note that only the right-hand side of the formula is required
+#'   for compensatory models.
+#'
+#'   For non-compensatory \code{itemtype}s (e.g., \code{'PC1PL'}) the formula must include
+#'   the name of the latent trait in the left hand side of the expression to indicate which
+#'   of the trait specification should have their intercepts decomposed (see MLTM; Embretson, 1984)
 #' @param quadpts number of quadrature points per dimension (must be larger than 2).
 #'   By default the number of quadrature uses the following scheme:
 #'   \code{switch(as.character(nfact), '1'=61, '2'=31, '3'=15, '4'=9, '5'=7, 3)}.