(a) Definition of the behavioural problems intended to screen by the instrument
Behavioural problems of children was defined by considering the different definitions given by other authors [19
], and by conducting review discussions with several experts in the fields of Pediatrics, Child Psychiatry, Community Medicine and Child Psychology. This definition was based on identification of behavioural problems of children aged 4-6 years that fulfil the following criteria.
Behaviours which give rise to significant disturbance to the psychological well being and the future life of the child.
Behaviours that need early intervention by professionals and the early intervention result in good prognosis.
Based on the above criteria, behavioural problems of children aged 4-6 years was defined in this study as: behaviours which seriously limit or delay access to and use of ordinary society and carry significant disturbance for child's current and future psychiatric status .
According to the definition the intended screening instrument would contain six domains: inattention, hyperactivity and impulsivity, aggression, impaired social interactions, abnormalities of communication and restricted, stereotyped pattern of behaviour [19–24]. It is acknowledged that most of the behavioural problems that resolve with time, without any special intervention will not be detected by this instrument.
(d) Ascertaining the final instrument using Delphi technique
The final instrument was ascertained from the preliminary list of 54 items using the Delphi technique. A panel of 15 experts in the areas of Community Medicine, Child Psychiatry, Paediatrics, Child Psychology and policy making were recruited. They were informed the objectives of the study and the definition of the behavioural problems that are intended to be identified using the instrument. They were told that the instrument was being developed to be administered by a lay interviewer or primary health care worker to the mother or the care giver of the child as a routine screening activity, in the community. The need for a simple and concise instrument was highlighted. To gain consensus of the above experts, three rounds of rating were carried out. During the first round, an open ended questionnaire was prepared on the preliminary list of 54 items. Then the participants were asked to rate each item on a five point scale as: 1. Most important; 2. Important; 3. Don't know; 4. Unimportant; 5. Should be deleted, with regard for inclusion in the screening instrument and give any comments or generate more items based on the objectives and definition used in the study. Items rated as "Most important" or "important" by more than 75% of the panel members and accepted new items generated by them were selected for the second round of rating. At the end of this round items positively rated by 80% of panel members were selected and suggested modifications were done accordingly . The final instrument which consisted of 15 items measuring six domains namely inattention (items 1,2 & 5), hyperactivity and impulsivity (items 3,4 & 6), aggression (items 7,8 & 9), impaired social interactions (items 10,11&15) abnormalities of communication (item 14) and restricted, stereotyped pattern of behaviour(items 12&13), was developed following the third round, and named as the Child Behaviour Assessment Instrument (CBAI). The average time taken for administration of the CBAI was five minutes.
An open ended question regarding the presence of any other behavioural problems was included at the end of the questionnaire to obtain other significant behaviours not included in the instrument. The response choices for each of the 15 items were provided as; "very often", "some times" and "never" and the scoring of 2, 1, 0 attributed to each of the these categories such that the lower value (0) indicated a lesser likelihood of having a behavioural problem where as the higher value (2) indicated a higher likelihood of having a behavioural problem. To ensure internal consistency of the questionnaire some of the items (1, 5, 10, 11, 14, and 15) were worded to assess positive behaviours and the responses were reversed scored. To quantify overall impact of each component of the above instrument, simple, unweighted count of event score, was developed by adding the individual score for each item which was ranging from 0 to 30 .
See the Additional file 1 for the CBAI including instructions for interviewers.
Translation of the developed instrument into local (the Sinhala) language was undertaken by a panel of individuals who were fluent in both English and Sinhala . They translated the instrument independently of one another, using clear simple language to cater the respondents. Then each item of the original English version of the instrument and its corresponding five translations were considered at a time for evaluation and consensus generation following which final translation achieved.
Pre testing of the developed instrument was carried out on a convenience sample of 50 mothers of children aged 4-6 years. Clarity and relevance of the items were assessed and certain modifications were made accordingly.