Measuring Job and Patient Satisfaction in presence of missing values: a case study with Interval Imputation

The evaluation of Satisfaction within a given Organization has a twofold perspective: from the customer/user and the employee point of view. The presented case study is set up in the Ophthalmology Departments of the hospital "Spedali Civili" in Brescia and Montichiari. Job and Patient Satisfaction are investigated by means of two structured questionnaires and composite indexes are obtained with statistical procedures. The construction of a Satisfaction index has to face two main statistical problems, the former related to the ordinal scale of Satisfaction judgements, the latter caused by the frequent presence of missing values. In this paper Nonlinear Principal Component Analysis is applied together with a specific technique for missing values treatment, called Interval Imputation.