Graph of b/w actual vs. estimation
1. Estimation of Errors Model:
The number of errors in a program can be estimated by using a linear or nonlinear regression model. A simple nonlinear regression model to estimate the total number of initial errors in the program, N, can be presented as follows:
2. Estimation of Complexity Model:
This model is used to estimate the software complexity, CR, using the time series approach. The software complexity model is summarized as follows:
3. Estimation of Failure Rate Model:
This model is used to estimate the failure rate of software. Given failure times t1, t2, .., tn, a rough estimate of the failure rate at the ith failure interval is
Curve Fitting models – Software Engineering
The curve fitting group models use statistical regression analysis to study the relationship between software complexity and the number of faults in a program, the number of changes, or failure rate. This group of models finds a relationship between input and output variables by using the methods linear regression, nonlinear regression, or time series analysis. The dependent variables, for example, are the number of errors in a program. The independent variables are the number of modules changed in the maintenance phase, the time between failures, programmers’ skill, program size, etc. Models included in this group are: Estimation of errors, Estimation of complexity, Estimation of failure rate. These are explained as following below.