In clasp, statistical objects have two parts, a class which stores the various parts of the object and a computing function which computes the value of the object from arguments. The define-statistic macro allows the definition of new statistical types. The define-statistic macro must be provided with all the information necessary to create a statistical object, that is, everything required to create a new class, everything required to create a computing function and some information to connect the two. This last part consists of a list of arguments and their types and a list which determines how the values of a statistical function should be used to fill the slots of a statistical object. When define-statistic is invoked, two things happen, first a class is defined which is a subclass of 'statistic and any other named `superclasses'. Second, a pair of functions is defined. `clasp-statistics::name' is an internal function which has the supplied `body' and `lambda-list' and must return as many values as there are slots in the class `name'. The function `name' is also defined, it is basically a wrapper function which converts its arguments to those which are accepted by `body' and then calls `clasp-statistics::name'. The parameter clasp:*create-statistical-objects* determines whether the wrapper function packages the values returned by the intern function into a statistical object or just returns them as multiple values. The `argument-types' argument must be an alist in which the keys are the names of arguments as given in `lambda-list' and the values are lisp types which those arguments will be converted to before calling the internal statistical function. The primary purpose of this is to allow for coersion of clasp variables to sequences, but any coercion which is allowed by lisp is acceptable. The `values' argument is intended to allow the programmer to specify which slots in the statistical object are filled by which of the values returned by the statistical function. By default, the order of the values is assumed to be direct slots in order of specification, inherited slots in order of specification in the superclasses which are also statistics.