model_mixed function

Mixed-format model

Common computations and operations for the mixed format model

model_mixed_gendata(n_p, n_3pl = 0, n_gpcm = 0, n_grm = 0, n_c, ...)

model_mixed_prob(t, items, D = 1.702)

model_mixed_info(t, items, D = 1.702, combine = TRUE)

model_mixed_lh(u, t, items, D = 1.702, log = FALSE, combine = TRUE)

Arguments

• n_p: the number of test takers
• n_3pl: the number of 3pl items
• n_gpcm: the number of gpcm items
• n_grm: the number of grm items
• n_c: the number of score categories for polytomous items
• ...: additional arguments
• t: ability parameters, a vector
• items: a list of '3pl', 'gpcm', and 'grm' items
• D: the scaling constant, default=1.702
• combine: TRUE to combine results from list to matrix
• u: the response data, a 2d matrix
• log: TRUE to return log-likelihood

Returns

model_mixed_gendata returns a list of generated responses, ability paramters and items

model_mixed_prob returns a list of probabilities for '3pl', 'gpcm', and 'grm' items

model_mixed_info returns a list or matrix of information

Examples

# generate 10 3pl items, 5 gpcm items and 5 grm items
model_mixed_gendata(10, n_3pl=10, n_gpcm=5, n_grm=5, n_c=3)
# generate 5 gpcm items and 5 grm items, 4 score categories each
model_mixed_gendata(10, n_gpcm=5, n_grm=5, n_c=4)
# generate 5 people and 4 items of each type
with(model_mixed_gendata(n_p=5, n_3pl=4, n_gpcm=4, n_grm=4, n_c=3), 
     model_mixed_prob(t, items))
     
# generate 10 people and 5 gpcm and 5 grm items
with(model_mixed_gendata(n_p=10, n_gpcm=4, n_grm=4, n_c=3), 
     model_mixed_prob(t, items))
with(model_mixed_gendata(10, 4, 4, 4, 3), model_mixed_info(t, items)) 
with(model_mixed_gendata(10, 0, 4, 4, 3), model_mixed_info(t, items)) 
with(model_mixed_gendata(10, 4, 4, 4, 3), model_mixed_lh(u, t, items))