---
title: "Model building, verification, validation steps"
subject: "Simulation and Modeling"
chapter: 7
key: "semester_8/simulation_and_modeling:model-building-verification-validation"
source: https://www.bctengineer.com/q/semester_8/simulation_and_modeling/model-building-verification-validation
site: BCT Engineering
---

# Model building, verification, validation steps

Simulation and Modeling · Chapter 7: Verification and validation of simulation models

- Asked in: 2072 Magh, 5 marks
- Video: [SMTL 04 Principles of Model-Building, Verification, and Validation](https://www.youtube.com/watch?v=WW0GREwW1_I) — Mihails Savrasovs
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_8/simulation_and_modeling/model-building-verification-validation
- Whole chapter: https://www.bctengineer.com/md/semester_8/simulation_and_modeling/chapter-7

## Question

Explain steps in model building, verification and validation with diagrams.

## Short answer

Model building: observe system, collect data, build conceptual model, program. Verification checks the program matches conceptual model through walkthroughs, tracing, and simple tests. Validation uses face validity, assumption tests, and input-output comparisons; calibration iterates if needed. Only a verified and validated model is used for experiments.

## Answer

Model building, verification and validation form one connected process. A model is first built from the real system, the program is verified against the conceptual model, and the final model is validated against the real system, with calibration repeated until the model is credible.

#### Steps in model building
1. **Observe the real system** and study how it works, including its interactions among components.
2. **Collect and analyse data**: record arrival and service times, fit distributions, and list assumptions.
3. **Build the conceptual model**: components, entities, state variables, events, level of detail and the structure of logic.
4. **Translate to an operational (computer) model** using a language or package.

#### Verification steps
- Ensure the program matches the conceptual model.
- Have another person read the code (structured walk-through).
- Trace entities and events by hand and compare with the output.
- Run with simple inputs for which the answer is known, such as a deterministic arrival and service time.
- Use a debugger, print state variables, and check that input parameters are read and used correctly.
- Check that output is reasonable when inputs are varied.

#### Validation steps (Naylor and Finger)
1. Get high **face validity** from users and experts.
2. Validate **assumptions** (structure and data).
3. Compare the model's **input-output** relationship with the real system's (statistical test or confidence interval).
4. If the model is not accurate enough, **calibrate**: change the model and repeat.

#### Diagram
```text
   Real system
   |         ^
   | abstract|  validation +
   v         |  calibration
 Conceptual  |
   model     |
   |         |
   | verification (program matches
   v          conceptual model)
 Operational model (program)
   |
   +-----> run, compare with real data
```

#### Iteration
If the comparison fails, go back to data, assumptions or logic, correct them and repeat. Only a model that has been verified and validated should be used for experiments and decisions.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which sequence matches the steps in model building?
   A. Conceptual model, observe system, code, collect data
   B. Observe the system, collect and analyse data, build conceptual model, translate to operational model
   C. Code the program, observe system, validate, collect data
   D. Collect data, run experiments, build conceptual model
   Answer: B. Building goes from observation and data to the conceptual model and then the computer model. (Key point: Model building order)

2. Which is a verification step?
   A. Running with simple inputs of known answer, such as deterministic arrival and service times
   B. Asking users if results are believable
   C. Comparing outputs with real data statistically
   D. Fitting distributions to data
   Answer: A. Known-answer test runs, walk-throughs, tracing and debugging check the program against the conceptual model. (Key point: Verification technique)

3. If the model is not accurate enough after the input-output comparison, what is done?
   A. Use the model anyway
   B. Delete the data
   C. Calibrate: change the model and repeat the comparison
   D. Stop and increase run length only
   Answer: C. Calibration modifies the model and the validation is repeated until the model is credible. (Key point: Validation step 4)

4. In the diagram, what links the conceptual model to the operational model?
   A. Validation
   B. Verification
   C. Calibration
   D. Replication
   Answer: B. Verification confirms the program matches the conceptual model, while validation and calibration relate model to the real system. (Key point: Diagram link)

## Related in Simulation and Modeling

- [Compare verification, validation, calibration](https://www.bctengineer.com/question.md?key=semester_8%2Fsimulation_and_modeling%3Averification-validation-calibration-compare) — Simulation and Modeling, chapter 7
- [Naylor and Finger validation approach](https://www.bctengineer.com/question.md?key=semester_8%2Fsimulation_and_modeling%3Anaylor-finger-validation) — Simulation and Modeling, chapter 7, asked 2×

## Related in other subjects

- [Verification versus validation; critical systems](https://www.bctengineer.com/question.md?key=semester_5%2Fsoftware_engineering%3Averification-vs-validation) — Software Engineering, chapter 7
- [Verification planning](https://www.bctengineer.com/question.md?key=semester_5%2Fsoftware_engineering%3Averification-planning) — Software Engineering, chapter 7