Lecture 14 provides knowledge of software metrics. The main contents of this chapter include all of the following: Why measure software, fundamentals of measurement theory, use case points. | Ivan Marsic Rutgers University LECTURE 14: Software Metrics Topics Why Measure Software Fundamentals of Measurement Theory Use Case Points Why Measure Software To estimate development time and budget To improve software quality Measurement Scale (1) Nominal scale – group subjects into categories Example: designate the weather condition as “sunny,” “cloudy,” “rainy,” or “snowy” The two key requirements for the categories: jointly exhaustive & mutually exclusive Minimal conditions necessary for the application of statistical analysis Ordinal scale – subjects compared in order Examples: “bad,” “good,” and “excellent,” or “star” ratings Arithmetic operations such as addition, subtraction, multiplication cannot be applied Measurement Scale (2) Interval scale – indicates the exact differences between measurement points Examples: traditional temperature scale (centigrade or Fahrenheit scales) Arithmetic operations of . | Ivan Marsic Rutgers University LECTURE 14: Software Metrics Topics Why Measure Software Fundamentals of Measurement Theory Use Case Points Why Measure Software To estimate development time and budget To improve software quality Measurement Scale (1) Nominal scale – group subjects into categories Example: designate the weather condition as “sunny,” “cloudy,” “rainy,” or “snowy” The two key requirements for the categories: jointly exhaustive & mutually exclusive Minimal conditions necessary for the application of statistical analysis Ordinal scale – subjects compared in order Examples: “bad,” “good,” and “excellent,” or “star” ratings Arithmetic operations such as addition, subtraction, multiplication cannot be applied Measurement Scale (2) Interval scale – indicates the exact differences between measurement points Examples: traditional temperature scale (centigrade or Fahrenheit scales) Arithmetic operations of addition and subtraction can be applied Ratio scale – an interval scale for which an absolute or nonarbitrary zero point can be located Examples: mass, temperature in degrees Kelvin, length, and time interval All arithmetic operations are applicable Subjective Metrics Subjective Metrics Use Case Points (UCPs) Size and effort metric Advantage: Early in the product development (after detailed use cases are available) Drawback: Many subjective estimation steps involved Use Case Points = function of ( size of functional features (“unadjusted” UCPs) nonfunctional factors (technical complexity factors) environmental complexity factors (ECF) ) Actor Classification and Weights Actor type Description of how to recognize the actor type Weight Simple The actor is another system which interacts with our system through a defined application programming interface (API). 1 Average The actor is a person interacting through a text-based user interface, or another system interacting through a
