We quite regularly use genetic algorithms to optimise over the ad-hoc functions we develop when trying to solve problems in applied mathematics. However it’s a bit disconcerting to have your algorithm roam through a high dimensional solution space while not being able to picture what it’s doing or how close one solution is to another. … Continue reading...
This is a very quick post just to share a quick tip on how to add non overlapping labels to a scatterplot in ggplot using a great package called directlabels. The trick is to make each point a single member group using an aesthetic like colour and then apply the direct.label function with the first.qp … Continue reading...
Following on from the previous post here is an R function for visualising correlations between the explanatory variables in your data set. An interesting example is the North Carolina Crime data set that comes with the plm package. This has the following continuous variables: crmrte crimes committed per person prbarr probability of arrest prbarr probability … Continue reading...
In marketing mix modelling you have to be very lucky not to run into problems with multicollinearity. It’s in the nature of marketing campaigns that everything tends to happen at once: the TV is supported by radio, both are timed to coincide with the relaunch of the website. One of the techniques that is often … Continue reading...
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
