Data quality control
The data collectors were residents and they trained for one day. The principal investigator had an ongoing supervision and reviewing of each completed data during the data collection to ensure the quality of data by checking filled formats for their completeness and consistency thought out the data collection period. Contamination of training materials and trainee between intervention and control group secured. Data collection instrument pretested by 5% of sample size before data collection, then any errors or ambiguity on the questionnaire were corrected and modified.