Requirement analysis - 要望 (demand) vs 要求 (request) vs 要件 (requirement)

During researching on requirement analysis, I found some useful articles, in both English and Japanese. So I decided to summarize the information, refined a bit then translate them into English (in case of Japanese). Hopefully it could come in handy in the future for me or anyone reading this post.

Requirement analysis

Let’s review a bit, first is the definition of requirement analysis: According from Wikipedia:

In systems engineering and software engineering, requirements analysis focuses on the tasks that determine the needs or conditions to meet the new or altered product or project, taking account of the possibly conflicting requirements of the various stakeholders, analyzing, documenting, validating and managing software or system requirements.

Short version: Requirement analysis is the process of defining, documenting and maintaining user expectations for a new software being built or modified.

Requirement analysis is the first step in system development, and it’s usually considered a critical factor to the success of a software or a project. Many software companies often bypass the requirements analysis phase of the software development process and jump directly to the implementation phase in an effort to save time and money. The result of such an approach often leads to exceeding budget, not meeting user needs or expectations and so one.

As the Tree swing cartoon illustrates. meme.jpeg

User request to system requirement

The table below defines the meaning of 要望 (demand), 要求 (request) and 要件 (requirement). The words are similar, but the content is different. I will also use a house building case as an example.

Explanation Example
要望 Demand A vague expression from customer perspective, customer’s idea, needs, what customer wants to accomplished, doesn’t want to do, usually can be understand as “It would be great if…” Customer wants to build a new house (just married, got kids etc)
要求 Request What customer want to do, but haven’t decided on the details, usually can be understand as “I want to…” Customer talks to architect, describe how they want the house to be (has a big living room, must have a front yard, separated parents and kid’s bedroom etc)
要件 Requirement How the system should be to fulfill customer’s needs How many stories, number of rooms, how big is each room, how high is the ceiling, number of windows
  • The classification above is subjective and is not based on any criteria nor standard.
  • The English translation is not 100% correct, but you can get the idea from the explanation.


Wikipedia - Requirements analysis

IPA - 家づくりで理解する要求明確化の勘どころ ~システム構築を成功させる要件定義のポイント~

IPA - 要求の明確化と合意形成

Requirement Analysis Techniques