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Lecture Software engineering: Lecture 14 - Ivan Marsic

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 http://en.wikipedia.org/wiki/Problem_Frames_Approach 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 http://en.wikipedia.org/wiki/Problem_Frames_Approach 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