Mokken Scale Procedure
msp varlist [, nodetails kernel(#) c(#) notest p(#) pairwise minvalue(#) nobon noadjust]
varlist is a list of two existing dichotomous or polytomous variables or more.
msp selects scales of dichotomous or polytomous items with the Mokken Scale Procedure (MSP) defined by Mokken (1971) and by Hemker and al. (1995).
nodetails does not display informations during the algorithm of selection.
kernel defines a kernel for the first scale, defined as the first # items of varlist.
c defines the level of the threshold c. The level of c is fixed, by default, at 0.3.
notest selects the scales whithout tests among the Loevinger H coefficient (Hjk>0): the new item with the maximal value for Hj>c is always selected.
p defines the significance level for the tests. The level of p is fixed, by default, at 0.05.
pairwise does no more delete all the individuals who have one or more missing values among all the items of varlist but, only these ones who have, for each pair of items, one or more missing values to these two items.
minvalue defines the minimum value of the coefficient Hjk for a pair of item composing a scale. This minimal value is fixed by default to 0.
nobon does no more correct the significance level of the test by the Bonferroni correction.
noadjust approximates the tests statistics like the MSP program (Molenaar et al. (2000)).
For detailed informations on the Mokken scale procedure, see Mokken (1971), Hemker and al. (1995) or the manual of the MSP software (2000).
msp runs with dichotomous or polytomous items.
msp necessitates the program loevh to compute.
r(dim) saves the number of built scales.
r(selection) saves a vector which contains, for each item, the scale where it is selected (0 if the item is unselected).
r(H#) saves the Loevinger's H coefficient of the #th scale.
r(nbitems#) saves the number of items selected in the #th scale.
r(scale#) saves the names of the items selected in the #th scale.
r(scalenum#) saves the numbers of the items selected in the #th scale.
. msp itemA1-itemA7
. msp itemA* itemB* , nodetails kernel(2)
. msp item* , c(0.2) nob pairwise
Hemker B. T., Sijtsma K. and Molenaar I. W., Selection of unidimensional scales from a multidimensional item bank in the polytomous Mokken IRT model, Applied Psychological Measurement, vol.19(4), 1995, pp. 337-352.
Mokken R. J., A theory and procedure of scale analysis. New-York/Berlin : De Guyter, 1971.
Molenaar I. W., Sijtsma K. and Boer P. User's manual of MSP5 for Windows. Groningen (The Netherlands): iec ProGAMMA, 2000.
help for loevh (if installed), help for mokken (if installed)
Jean-Benoit Hardouin, PhD, assistant professor EA 4275 "Team of Biostatistics, Clinical Research and Subjective Measures in Health Sciences" University of Nantes - Faculty of Pharmaceutical Sciences 1, rue Gaston Veil - BP 53508 44035 Nantes Cedex 1 - FRANCE Email: email@example.com