A Classification Updating Procedure Motivated by High Content Screening Data

The current paradigm for the identification of candidate drugs within the pharmaceutical industry typically involves the use of high throughput screens (HTS). High content screening (HCS) is the term given to the process of using an imaging platform to screen large numbers of compounds for some desirable biological activity. Classification methods have important applications in high content screening experiments where they are used to predict which compounds have the potential to be developed into new drugs. In this paper a new classification method is proposed for batches of compounds where the rule is updated sequentially using information from the classification of previous batches. This methodology accounts for the possibility that the training data are not a representative sample of the test data and that the underlying group distributions may change as new compounds are analysed. This technique is illustrated on an example data set using linear discriminant analysis, k-nearest neighbour and random forest classifiers. Random Forests are shown to be superior to the other classifiers and are further improved by the additional updating algorithm in terms of an increase in the number of true positives as well as decreasing the number of false positives.