Impact Analysis (IA)

Impact Analysis - ToolsHero

This article explains the Impact Analysis in a practical way. After reading it, you will understand the basics of this powerful decision making method.

What is an Impact Analysis?

In 1996, American software engineers Robert S. Arnold and Shawn A. Bohner were the first to write about Impact Analysis (IA) in their book ‘Software Maintenance’.

Impact Analysis is a quantitative research method, in which a study is carried out concerning the impact that an error can have on the other parts of a configuration. It is about identifying the potential consequences of a change within complex product development. As a result, predefined requirements can be improved.

3 types

According to Bohner and Arnold, there are several types of IA, such as ‘traceability’ and ‘dependence’, both of which they identified. The third type, ‘experiential’, was later added after other studies.

Traceability

The traceability variant of IA establishes links between requirements, specifications, design elements and tests. This allows the scope of a change to be determined, analysed and monitored. In complex projects involving many intermediate steps, trying to manually determine what will be affected by a change and which people will be affected is time consuming and prone to errors. Traceability automatically marks changes so that it is clear which parts and people are affected by a change. Understanding the impact of change enables teams to respond more quickly and accurately to change requests.

Dependence

In the dependency variant of IA, the links and relationships between parts and variables become clear. When it is clear in advance who and what are dependent upon one another, it is immediately clear what effect certain changes will have. This determines that the dependency variant of IA takes place at a more detailed level.

Experiential

The experiential variant of IA focuses on the fact that the impact of changes is strongly related to how experts experience this. Their prior knowledge plays an important role in this. What happened in a previous, similar situation and what was its impact? Together, a team is therefore able to predict and even determine the consequences of a change.

Impact Analysis steps

To make IA run as smoothly as possible, Bohner and Arnold advise to do so step by step. Usually such a step-by-step plan does not take more than a few hours. The investment in drawing up a step-by-step plan will ultimately lead to a sensible investment in the (limited) resources.

Step 1

Determining the order in which the tasks will be carried out, their relationship and interdependence and the extent to which they can be carried out simultaneously. When the order is clear, the critical path can be taken into account; the time needed to complete the entire project with as little wiggle room as possible.

Step 2

The change that may be implemented may have an impact on the critical path. Which is why it is good to look at this in advance. As soon as a modification of a subtask affects the duration of the critical path, there is a good chance that the project deadline will not be met.

Step 3

It would be wise to estimate what kind of affect a possible change will have in advance. The length of time and the budget play a particularly important role in this. Priorities can be set based on this estimate.

Final Step

As a final step, it is very important to inform all stakeholders in the project about the Impact Analysis. They can use all this information to make the right decisions. It will also depend as to whether they accept the proposed changes or not. Thus, it is important for them to have the result of the changes in mind, so that they are motivated to implement it.

Waste

It is useful to carry out a good Impact Analysis to avoid wasting valuable energy and time. When it is estimated that an improvement in a certain production process will take 6 weeks, it is a huge disappointment for several parties when it eventually takes 6 months. Customers, sales staff, production department and management become the victims of this letdown. With a good Impact Analysis, there would have been a clear and reliable estimate on the table. While the analysis may have also taken time, it would have also clearly shown that the change in the production process could take up to 3 months to implement. Informing all stakeholders would have saved a lot of annoyance. By setting the wrong expectation beforehand, a lot of energy was wasted, which in turn caused the customer to leave.

Risks

An Impact Analysis can also be used to focus on the risks associated with the changes. By definition, a change does not necessarily have to lead to improvement. If it does lead to improvement, then one must be honest and open to the possibility that risks cannot be excluded. Possible risks often affect the resources used, the overall planning and the effort that employees have to make. The latter are expected to be flexible and to welcome changes. In reality, this does not always work out, and it constitutes a risk. When employees are not prepared to implement changes, even though it is crucial to implement them, errors will remain part of the process.

It’s Your Turn

What do you think? What is your experience with using an Impact Analysis (IA)? Do you have any additions to the above? Are there tips or good experiences that you want to share with our readers?

Share your experience and knowledge in the comments box below.

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More information

  1. Arnold, R. S. (1996). Software change impact analysis. IEEE Computer Society Press.
  2. Arnold, R. S., & Bohner, S. A. (1993, September). Impact analysis-towards a framework for comparison. In 1993 Conference on Software Maintenance (pp. 292-301). IEEE.
  3. Bohner, S. A. (2002). Software change impacts-an evolving perspective. In Software Maintenance, 2002. Proceedings. International Conference on (pp. 263-272). IEEE.

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