A shiny app to visualize effects non-linearly modeled applying fractional polynomials, natural (restricted cubic) splines, or linear b-splines.
For each method the relevant parameters can be changed and the resulting non-linear effect can be graphically assessed.
Users can visualise first- or second-degree fractional polynomials, linear b-splines with 4 degrees of freedom and natural splines with 3 degrees of freedom. Additionally, if one assumes a specific residual standard error, one can visualise how the outcome y could look like. Are these data realistic in a biomedical setting?
The shiny app is currently hosted at https://biometrician.shinyapps.io/nonlinear_visualisation/.