Indirect Equating via an Anchor Test — leunbach_indirect

Performs indirect equating from Test A to Test C via an anchor Test B. This chains two direct equatings: A → B and B → C.

Usage

leunbach_indirect_equate(
  fit_ab,
  fit_bc,
  direction_ab = c("1to2", "2to1"),
  direction_bc = c("1to2", "2to1"),
  method = c("optimize", "newton"),
  verbose = FALSE
)

Arguments

fit_ab: A leunbach_ipf object for the A-B equating (Tests A and B)
fit_bc: A leunbach_ipf object for the B-C equating (Tests B and C)
direction_ab: Direction for A-B equating: "1to2" or "2to1"
direction_bc: Direction for B-C equating: "1to2" or "2to1"
method: Optimization method: "optimize" (default) or "newton"
verbose: Print detailed output

Value

A list of class "leunbach_indirect" containing:

equating_table: Data frame with source scores, expected equated scores, and rounded scores
eq_ab: Direct equating object for A → B
eq_bc: Direct equating object for B → C
fit_ab: Original leunbach_ipf object for A-B
fit_bc: Original leunbach_ipf object for B-C

Details

Indirect equating works by chaining two direct equatings:

For a score x on Test A, find the expected score on Test B (typically non-integer)
Find expected Test C scores for the integer B scores below and above
Interpolate to get the expected Test C score for the non-integer B score
Round to get the equated integer score

Examples

# Fit models for A-B and B-C
fit_ab <- leunbach_ipf(data_ab)
#> Error: object 'data_ab' not found
fit_bc <- leunbach_ipf(data_bc)
#> Error: object 'data_bc' not found

# Indirect equating:  Test1 of fit_ab → Test2 of fit_ab → Test2 of fit_bc
indirect <- leunbach_indirect_equate(fit_ab, fit_bc, 
                                      direction_ab = "1to2", 
                                      direction_bc = "1to2")
#> Error: object 'fit_ab' not found
print(indirect)
#> Error: object 'indirect' not found