I have a binary response variable (hail) and multiple continuous predictor variables. My aim is to understand the linear/non-linear relationship of the predictors to the response to be able to justify the use of a linear or non-linear model.
I got the advice to use conditional density plots (
cdplot() in R). Since I experienced some problems due to the distribution of my data (SO question), I also tried spinograms (
spineplot()). To visualize point densities of my x-variable, I used
lattice::densityplot() since "conditional densities are more reliable for high-density regions of x".
I read about the interpretation of
cdplot()here. 'Spinograms' and 'Cond. Dens. plot' show the probability of hail/NoHail for a given temperature.
Spinograms provide a grouped x-axis view based on a
hist()call on the x-axis variable. 'Cond. Dens. plot' shows basically the same as Spinograms, just smoothed?
I´m afraid of the high probabilities of
cdplot()in the regions of -18 to -10 since only a few points of my x-variable fall into this range and therefore this region is "less reliable".
How to interpret the differences of
cdplot()in the region of -18°C?
spineplot()shows a probability of around 0.1 while
cdplot()shows a peak with roughly 0.3?
I would conclude that
spineplot()shows a non-linear relationship while
cdplot() shows this as well, however with a slight tendency to a negative linear relationship?