(methods) from super-classes. The deeper the inheritance tree,the more complex the design. Many different object classes mayhave to be understood to understand the object classes at theleaves of the tree.Method fan-in/fan-outThis is directly related to fan-in and fan-out as described aboveand means essentially the same thing. However, it may beappropriate to make a distinction between calls from othermethods within the object and calls from external methods.Weighted methods perThis is the number of methods that are included in a classclassweighted by the complexity of each method. Therefore, a simplemethod may have a complexity of 1 and a large and complexmethod a much higher value. The larger the value for thismetric, the more complex the object class. Complex objects aremore likely to be more difficult to understand. They may not belogically cohesive so cannot be reused effectively as super-classes in an inheritance tree.Number of overridingThis is the number of operations in a super-class that are over-operationsridden in a sub-class. A high value for this metric indicates thatthe super-class used may not be an appropriate parent for thesub-class.Measurement analysis•It is not always obvious what data means •Analysing collected data is very difficult. •Professional statisticians should be consulted if available. •Data analysis must take local circumstances into account. Measurement surprises•Reducing the number of faults in a program leads to an increased number of help desk calls •The program is now thought of as more reliable and so has a wider more diverse market. The percentage of users who call the help desk may have decreased but the total may increase; •A more reliable system is used in a different way from a system where users work around the faults. This leads to more help desk calls. ZIPF’s Law•Zipf's Law as "the observation that frequency of occurrence of some event (P), as a function of the rank (i) when the rank is determined by the above frequency of occurrence, is a power-law function Pi~ 1/iawith the exponent aclose to unity (1)."