Data are passed through filterGraph
and normalizeData
.
Then the ‘unidim_adapt’ model is fit to each item individually.
A larger varCorrection
will obtain a more accurate
scale
, but is also more likely to produce an intractable
model. A good compromise is between 2.0 and 4.0.
calibrateItems(df, iter = 2000L, chains = 4L, varCorrection = 3,
maxAttempts = 5L, ...)
a data frame with pairs of vertices given in columns pa1
and pa2
, and item response data in other columns
A positive integer specifying the number of iterations for each chain (including warmup).
A positive integer specifying the number of Markov chains.
A correction factor greater than or equal to 1.0
How many times to try re-running a model with more iterations.
Additional options passed to
stan
. The usual choices are iter
for
the number of iterations and chains
for the number of
chains.
A data.frame (one row per item) with the following columns:
Name of the item
Number of iterations per chain
Number of divergent transitions observed after warmup
Number of times the treedepth was exceeded
Number of chains with low E-BFMI
Minimum effective number of samples across all parameters
Maximum Rhat across all parameters
Median marginal posterior of scale
Median variance of theta (latent scores)
Vehtari, A., Gelman, A., Simpson, D., Carpenter, B., & B<U+00FC>rkner, P. C. (2019). Rank-normalization, folding, and localization: An improved \(\widehat R\) for assessing convergence of MCMC. arXiv preprint arXiv:1903.08008.
# NOT RUN {
result <- calibrateItems(phyActFlowPropensity) # takes more than 5 seconds
print(result)
# }
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