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# Challenges in Estimating Software Development: Complicated vs. Complex Processes
- URL: https://nolongerset.com/estimating-complicated-vs-complex/
- Published: 2023-09-13T19:02:06.000Z
- Updated: 2026-05-08T12:35:34.000Z
- Description: In software development, some processes are easier to estimate than others. Whether the process is complex or complicated has a profound impact on estimate reliability.
- Author: Mike Wolfe
- Tags: Business, #Import 2026-05-20 02:59

Estimating software development is a tricky proposition.

For context, I find it helpful to understand the difference between [complicated and complex processes](https://nolongerset.com/complex-vs-complicated/):

- A **complicated** process involves many moving parts, but they interact from one to the next in a **linear and predictable** way.
- A **complex** process also involves many moving parts, but they interact with each other in **random and unpredictable** ways.

For example, migrating the data itself from a backend Access database to a SQL Server database is a *complicated* process. There are many steps involved, but each step is well-defined and predictable. 

On the other hand, updating the front-end Access application following a migration of the backend data is a *complex* process. It’s difficult to anticipate how the data migration will affect the various forms, reports, and data-related code.

## Impact on Software Estimates

Whether a process is complex or complicated has a profound impact on how confident we can be in our estimates:

- We can produce a **reliable estimate** for a **complicated** system.
- Estimates for a **complex** system are much **less reliable**.

## Accounting for Estimate Volatility with Ranges

One way to deal with this reality is to use range estimates rather than single values.

Estimates where we have high confidence in how long it will take to complete a task will have narrow ranges, whereas estimates for more complex tasks will tend to have wider ranges.