• Our seminars are held weekly on a Tuesday afternoon and showcase the latest public health research by the School’s researchers, adjuncts and visitors. 
  • No RSVPs required, all are welcome.
  • For more information about our seminar program, please email med.research.sph@uq.edu.au
Seminar recordings

A selection of seminar recordings is available online to users with a UQ username and password. 

Non-linear Associations in Health Research. Presenter Dr Darsy Darssan

2 March 2021 1:00pm
Unless a variable is compared with itself, the relationship among variables is unlikely to be linear. Chopping continuous variables into intervals to observe non-linearity is a biased, inefficient approach. Categorising continuous covariates to obtain interpretable estimates such as odds ratios is a fallacious argument because the resulting estimate's interpretation depends on the exact distribution of the continuous variable. Cutpoints used for categorising continuous variables are arbitrary, manipulatable and do not replicate in other studies. This includes statistical cutpoints such as cutting at the median or tertiles. The modern computing power leaves no room for linear models unless guided by a credible scientific theory that asserts linear relationships among the variables. The best way to check a linear association is to fit a non-linear model and see if it looks close to linear. In this presentation, we will discuss the available methods to measure the non-linear associations in health research. We will use data from women's health, COVID-19 and NHANES to illustrate the techniques.