Longitudinal item response theory models in R -

Longitudinal item response theory models in R -

i'm trying fit longitudinal item response theory (irt) models in r. have test administered @ multiple measurement occasions. i'd examine individuals' growth curves of factor scores (i.e., ability levels) graded response models (grms). have used ltm bundle in r fit cross-sectional grm models in irt, it's not clear me how (or whether it's possible in ltm) extend models handle repeated measures of same items across time. how can fit growth curves longitudinal grm factor scores see changes in means/variances of ability levels on time? if isn't possible ltm package, packages/functions permit this? specific code examples appreciated.

here empirical examples similar i'm looking (except examples utilize rasch model binary items i'm using grms polytomous data):

mcardle, j. j., grimm, k. j., hamagami, f., bowles, r. p., & meredith, w. (2009). modeling life-span growth curves of cognition using longitudinal info multiple samples , changing scales of measurement. psychological methods, 14, 126-149. doi: 10.1037/a0015857

mcardle, j. j., & grimm, k. j. (2011). empirical illustration of alter analysis linking longitudinal item response info multiple tests. in a. a. davier (ed.), statistical models test equating, scaling, , linking (pp. 71-88): springer: new york.

r mixed-models