Shulou(Shulou.com)06/03 Report--

The methods used to estimate the workload of software projects include expert method and analogy method, analogy method and equation method. In the practice of software estimation, analogy method and analogy method are also commonly used estimation methods, but many people are confused about the application scope and estimation steps of the two methods. Now the author will introduce these two estimation methods in detail.

1. Analogy

Analogy is the method of comparing some attributes of the project with a similar set of baseline data to obtain an estimate of the project workload, duration or cost to be estimated. Analogy is the method of determining the predicted value of a target item based on a large sample of historical item data, usually using the 50th percentile as a reference rather than an average. Analogy method shall be selected for estimation, and items with the same main attributes shall be selected from the baseline database for comparison according to the main attributes of the items.

Analogy is suitable for evaluating projects that are similar to historical projects in terms of application area, system size, environment and complexity, and estimates are obtained by comparing new projects with historical projects. The accuracy of analog estimates depends on the completeness and accuracy of historical project data. Therefore, one of the prerequisites for using analogy method well is to establish a good post-project evaluation and analysis mechanism and establish baseline data for relevant attributes of historical projects.

Scope of application:

When the requirements are extremely vague or uncertain, if there is a set of baseline data with similar attributes (such as scale, application type, complexity, development team experience, etc.) to the project, the analogy method can be directly used to make full use of the baseline data to estimate the workload. Analogies can be benchmarked at the overall project level or at the subsystem level.

Estimation process:

1) Determine the attribute characteristics of the project to be estimated, such as the scale, complexity, application type, business field, experience and ability of the developer, etc. of the system.

2) Query the historical database and filter the "most similar" item attribute data.

3) If the attributes of the project to be estimated are similar to the main attributes of historical projects, the reasonable workload range of the project to be estimated can be directly obtained according to the baseline data of historical projects.

4) If there are too few historical items satisfying the main attributes of the item to be estimated at the same time, compare each attribute of the item to be estimated with the baseline data of the corresponding attribute of the historical item, and then calculate the average value of P25/P50/P75 as the estimated value.

5) In general, P50 workload data is taken as the most likely value of the project workload to be estimated.

Application Example 1:

Project Scope Description: A newly developed cockpit project for a bank to support graphical display and decision analysis of finance-related business data, such as business indicators, performance indicators, financial indicators, risk indicators, regulatory indicators, etc., using dashboard technology to comprehensively display the status quo and target completion progress to help understand whether the current business indicators are balanced and whether the market scale has a good development trend.

Identify the main attributes of the project to be estimated, namely: application type (BI), business area (bank), new development project.

After querying the enterprise benchmark database, it was found that the company had done 55 projects with basically the same attributes as the projects to be estimated.

The query results are as follows:

From the data in the table, it can be concluded that the most likely workload of the project to be estimated is 3845 person-hours (P50), and the reasonable workload range is between 3366 person-hours (P25) and 4210 person-hours (P75).

Application Example 2:

Project Scope Description: Develop a set of settlement reimbursement review and asset management system for a group enterprise to support the filling, review and approval of reimbursement documents of the company, and support the application, approval of fixed asset procurement and asset borrowing, allocation and elimination management.

By identifying the main attributes of the project to be estimated, three main attributes of the project can be identified as new development type, business field and application type, namely "new development,""group enterprise" and "business processing."

After querying the enterprise benchmark database, it is found that only 5 projects meet the three screening conditions at the same time, which is too few and has little reference value. Therefore, select a single attribute to compare, the query results are as follows:

From the data in the table, it can be calculated that the most likely workload of this project is 5238 people, and the calculation method is (5500+5240+4975)/3. A reasonable range for workload estimation is between 4744 person-hours and 5938 person-hours (averaged using P25 and P75 values, respectively).

2. Analogy

Analogy method refers to the method of comparing some attributes of this project with the data of one or several completed projects with high similarity, and obtaining the estimated workload, duration or cost of the project to be estimated after appropriate adjustment. Analogy method is selected for estimation. Usually, only 1~2 highly similar projects are referred to, and appropriate adjustments are made according to the differences between the project to be estimated and the reference project.

Scope of application:

1) When the demand is extremely vague or uncertain, it is difficult to estimate the workload. If there are highly similar historical projects at this time, the analogy method can be directly used to make full use of historical project data for estimation.

2) Apply assessment of some similar projects to historical projects in terms of business area, application type, environment and complexity, etc., and estimate by comparing new projects with historical projects.

3) The accuracy of the method's estimates depends on the completeness and accuracy of the completed project data, and the similarity between the two projects. If there is no similar project, the method cannot be applied.

Estimation process:

1) Identify the main attributes of the project to be estimated.

2) Look for similar historical projects that the organization has done.

3) Compare historical projects, mark difference points, and calculate the workload of the project to be estimated after adjustment.

Application examples:

The following projects are customized and developed based on the product framework submitted by the bank supervision of a company and according to the submission system required by the People's Bank of China and CBRC. Customers A and B in the example belong to city commercial banks.

Project Scope Description: Develop a regulatory filing system for Bank B using the company's own product framework. The banking business system includes core business system and credit management system. The data submitted for supervision come from these two systems. After data extraction, cleaning and summary, they are reported to the People's Bank of China and CBRC respectively according to requirements.

Historical Project: The Company has developed a similar system for Bank A and has been put into operation. According to statistics, the total workload of project development is 75 person-days, of which the workload of supervision and submission is 60 person-days, and the workload of intra-bank statement is 15 person-days, that is, Bank A adds 3 customized intra-bank statements on the basis of supervision and submission business function.

Demand difference: After analyzing the customer projects of Party A and Party B, it is confirmed that the application types of the two are the same, the project complexity is similar to the business field, and the project scope in terms of regulatory submission is the same, but Bank B does not put forward additional development requirements for intra-bank statements.

Based on the above information, it is estimated that the most likely workload of Customer B's project is 60 person-days by analogy, which is the same as the development workload of Bank A in the regulatory submission part.

Analogical and analogical estimates both rely on historical data for projects. Analogical estimates require organizations to establish baseline databases, while analogical estimates require new and historical projects to have highly similar partial attributes. (The copyright of this article belongs to Beijing Software Cost Evaluation Technology Innovation Alliance, and the source should be indicated for reprinting)

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.