Imputation by the mean score should be avoided when validating a Patient Reported Outcomes questionnaire by a Rasch model in presence of informative missing data

Table 1 Summary table of the characteristics of the imputation methods used to handle missing data

Method	Ability of the individual	Difficulty of the item	Addition of a random process	Likelihood based approach
NOIMP
LD
WORST
PMS	X		X
IMS		X	X
CIM	X	X	X
ICS	X	X
LOG	X	X	X	X
MOK	X	X
RAS	X	X	X	X
RAI	X	X		X

ISSN: 1471-2288