A cross-sectional survey was conducted on a large sample of fishing net textile workers in factories in Khon
Kaen province during the period from February to April, 2010. Individuals were randomly invited to participate
in the study by face-to-face communication. The minimum necessary sample size for the study for reliable estimation of the proportion (p) of the worker population experiencing LBP was based on a 95% con-
fidence interval (CI). A pilot study revealed that 36% of textile industry workers experience some form of LBP.
Using a precision in estimation of 10% and the sample size calculation formula for an approximately infinite
population (Chirawatkul, 2009), the necessary sample was calculated to be n = 683.
The survey was hand delivered to each worker with an invitation letter and information about the study. Workers completed the questionnaire independently, and researchers made appointments a few days later to return to collect the questionnaires. The Human Ethics Committee of Khon Kaen University (KKU) approved the study protocol.