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# irtplay\_1.4.1 (2020-02-21)

o Included the function ‘run\_flexmirt’ to implement flexMIRT software
(Cai, 2017) through R.

o Applied a prior distribution to the slope parameters of the IRT 1PL
model when the slope parameters are constrained to be equal in the
function of ‘est\_item’.

o Fixed a problem of using staring values to estimate item parameters in
the function of ‘est\_item’.

# irtplay\_1.4.0 (2020-01-23)

o Fixed a non-convergence problem of the maximum likelihood estimation
with fences (MLEF) in the function of ‘est\_score’.

o Updated the description and introduction of the package.

o Updated the documentation to explain how to implement the function
“est\_item” in more detail.

o Updated the README.md file to explain how to implement the function
“est\_item” in more detail.

# irtplay\_1.3.0 (2019-11-17)

o Included the function ‘llike\_score’ to compute the loglikelihood
function of ability for an examinee.

o Updated the function ‘est\_item’ to find better starting values for
item parameter calibration.

o Updated the function ‘est\_item’ to exclude items that contains no
item response data during the item parameter estimation.

o Updated the function ‘est\_item’ to count the number of item responses
for each item used to estimate the item parameters.

o Updated the function ‘est\_score’ to find better starting values when
MLE is used.

o Updated the function ‘est\_score’ to address NaNs of gradient values
and NaNs of hessian values when MLE, MLEF, or MAP is used.

o Fixed a problem of the function ‘est\_score’, which returned an error
message when a vector of an examinee’s response data was used in the
argument of ‘x’.

# irtplay\_1.2.0 (2019-10-16)

o Fixed a problem of the function ‘est\_score’, which returned an error
message when only one dichotomous item or one polytomous item was
included in the item meta data set.

o Fixed a problem of the function ‘est\_item’, which returned an error
message when the inverse of hessian matrix is not obtainable.

o Included the ‘maximum likelihood estimation with fences’ scoring
method (Han, 2016) in the function ‘est\_score’.

o Included the ‘inverse test characteristic curve (TCC)’ scoring method
(e.g., Stocking, 1996) in the function ‘est\_score’.

o Included the function ‘llike\_item’ to compute the loglikelihood
values of items.

# irtplay\_1.1.0 (2019-09-15)

o For the function ‘est\_item’, default parameters of a-parameter prior
distribution were revised

o Updated the function ‘est\_item’ to find better starting values for
item parameter calibration.

o Updated the function ‘est\_score’ to estimate an ability in a brute
force way when MLE or MAP fails to find the solution.

o Updated the function ‘irtfit’ to compute the likelihood ratio
chi-square fit statistic (G2; Mckinley & Mills, 1985).

# irtplay\_1.0.0 (2019-08-21)

o initial release on CRAN
