@article {Cao683, author = {Sissi Cao and Rahim Moineddin and Marcelo L Urquia and Fahad Razak and Joel G Ray}, title = {J-shapedness: an often missed, often miscalculated relation: the example of weight and mortality}, volume = {68}, number = {7}, pages = {683--690}, year = {2014}, doi = {10.1136/jech-2013-203439}, publisher = {BMJ Publishing Group Ltd}, abstract = {We present three considerations in analysing the association between weight and mortality, as well as other relations that might be non-linear in nature. First, authors must graphically plot their independent and dependent variables in a continuous manner. Second, authors should assess the shape of that relation, and note its shape. If it is non-linear, and specifically, J-shaped or U-shaped, careful consideration should be given to using the {\textquoteleft}best{\textquoteright} statistical model, of which multivariate fractional polynomial regression is a reasonable choice. Authors should also refrain from truncating their data to avoid dealing with non-linear relations.}, issn = {0143-005X}, URL = {https://jech.bmj.com/content/68/7/683}, eprint = {https://jech.bmj.com/content/68/7/683.full.pdf}, journal = {Journal of Epidemiology \& Community Health} }