ABSTRACT
This chapter is concerned with reliability of performance analysis systems and builds on previous work done in this area. The chapter commences by discussing the measurement issues of validity, objectivity, reliability and representativeness of sports performance data. There is a distinction between action variables and performance indicators, both of which can be evaluated for reliability. The chapter then uses an example of rally-ending shots in squash to illustrate two reliability statistics; percentage error and kappa. The final section of the chapter is about meaningful reliability assessment where we relate the level of reliability to the analytical goals of investigations. Essentially we wish to test whether data are reliable enough for the purposes they are going to be used for.
