Software Reliability: Probability (CE202 PDF)

Software reliability: probability " Calculating probability of events CE202 Software Engineering, Autumn term Dr Cunjin Luo, School of Computer Science and Electronic Engineering, University of Essex 1  What is probability? } It is a real number in the range 0..1 } 0 means t...

Software reliability: probability " Calculating probability of events CE202 Software Engineering, Autumn term Dr Cunjin Luo, School of Computer Science and Electronic Engineering, University of Essex 1  What is probability? } It is a real number in the range 0..1 } 0 means that there is no chance that that event would occur } 1 means that it is absolutely going to occur } It represents the chance that a certain event will occur } Examples: } Consider the coin toss, the probability of having the head is 0.5, which means that there is a 50% chance that it will be head } There are only two events that can occur in a coin toss. One is head and the other is tail. So, the probability of having head in a coin toss would be 0.5 } The probability for rain tomorrow: 0.14 (it could be any number between 0 to 1). It is based on statistical analysis& 2 Prob. of discrete events } The first example we discuss is the probability of having a coin toss. We just have two possible events, either head or tail } Probability for testing 3 OO Analysis & Design: mechanisms of abstraction } Fundamentally: the same abstraction mechanisms as object-oriented programming: } Encapsulation: classes and objects } Other possible modularization techniques: interfaces, packages/namespaces } Inheritance } Generalization/specialization } Subtyping } Subclassing } Polymorphism } Overloading } Dynamic binding 4  Encapsulation 5 Objects An object is: