[Empirical basis of the Questionnaire for Crying, Feeding and Sleeping].

The Questionnaire for Crying, Feeding and Sleeping of an infant, constructed based on theory and factor analysis, is assessed for internal consistency, inter-correlations, and its relation to a behaviour diary. A clinical and a non-clinical sample are compared. The sample of in total 704 infants younger than one year consists of different subsamples. To test the differences between a clinical and a non-clinical sample assessed with the questionnaire, data of 134 infants brought to the outpatient unit for parents with their infants and toddlers and a matched sample are used. The principal components analysis results in three well-interpretable scales correlating with each other, which all show a high internal consistency. The connections to the diary records and the differences between the means of the clinical and the non-clinical sample are found in the expected directions. The results of the Questionnaire for Crying, Feeding and Sleeping, including the criterion of Wessel, are consistent with the behaviour diary as well as the clinical diagnostics. The Questionnaire for Crying, Feeding and Sleeping shows validity according to these criteria and can therefore be used in research and clinical practise for the assessment of problems concerning crying, feeding and sleeping in the first year of life.