Lack of "statistically significant" association does not exclude causality.

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[2]  Andrew C Ward,et al.  Epidemiologic Perspectives & Innovations Open Access the Role of Causal Criteria in Causal Inferences: Bradford Hill's "aspects of Association" , 2009 .

[3]  Simon Dagenais,et al.  Causal assessment of occupational lifting and low back pain: results of a systematic review. , 2010, The spine journal : official journal of the North American Spine Society.

[4]  B. Kwon,et al.  Causal assessment of awkward occupational postures and low back pain: results of a systematic review. , 2010, The spine journal : official journal of the North American Spine Society.

[5]  Simon Dagenais,et al.  Causal assessment of occupational standing or walking and low back pain: results of a systematic review. , 2010, The spine journal : official journal of the North American Spine Society.