The LoudRun metafeature is a nice toy example, but there are not many domains for which LoudRun is of practical use. When we extend the concept of metafeatures to real-world problems, we encounter some difficulties. In this section, we discuss some of these issues; others will manifest themselves in the remainder of the thesis. In order to understand these issues, it is necessary to first consider such a real-world domain, and some of the data from it.