What is a computer model?

a representation of a real system, built from data and rules. It is used to predict what would happen.

Which is a use of computer modelling?

forecasting the weather. Data about the atmosphere is used to predict what will happen next.

Which is an advantage of using a computer model?

Dangerous situations can be tested safely. Nothing real is put at risk.

Why might the results of a model be wrong?

The data or rules used may be incomplete or inaccurate. A model can only use what it has been given.

A spreadsheet is used to see how monthly savings change if spending is cut. This is an example of:

a "what if" model. An input is changed to see the effect.

Computer modelling · Cambridge IGCSE Information & Communication Technology

In plain words

Before a bridge is built, engineers want to know whether it will stand up in a storm. They cannot test that on the real thing. So they build the bridge inside a computer, out of numbers and rules, and send a storm at it there.

4 things to know

A computer model is a representation of a real system, built from data and mathematical rules. Changing the inputs shows what would happen: a "what if" question.
Uses: personal finance, bridge and building design, flood water management, traffic management and weather forecasting.
Advantages: it is cheaper than building the real thing, and safer, since dangerous situations can be tested without risk. Many situations can be tried quickly, and slow processes can be speeded up.
Disadvantages: a model is only as good as its data and rules, so results can be wrong. Not every factor of real life can be included. Models can be expensive to set up, and people may trust the results too much.

Worked example

A town council models what would happen to its streets if the river rose by two metres. Give two advantages of using a model.

It is impossible to make the real river flood for a test, and it would be dangerous if they could.
Different heights of water and different flood defences can be tried in minutes, at little cost.

Tips and tricks

"What if" is the phrase for what models are used for.
A disadvantage is always available: real life is more complicated than the model, so the prediction may be wrong.

5 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

Computer modelling: 5 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

What is a computer model?
- a picture of a computer
- a representation of a real system, built from data and rules (the answer)
- a database of customers
- a robot
It is used to predict what would happen.
Which is a use of computer modelling?
- sending an email
- forecasting the weather (the answer)
- scanning a bar code
- printing a poster
Data about the atmosphere is used to predict what will happen next.
Which is an advantage of using a computer model?
- It is always exactly right.
- Dangerous situations can be tested safely. (the answer)
- It needs no data.
- It can replace all real testing.
Nothing real is put at risk.
Why might the results of a model be wrong?
- Computers cannot do arithmetic.
- The data or rules used may be incomplete or inaccurate. (the answer)
- Models do not use data.
- The screen is too small.
A model can only use what it has been given.
A spreadsheet is used to see how monthly savings change if spending is cut. This is an example of:
- control
- direct data entry
- a "what if" model (the answer)
- video-conferencing
An input is changed to see the effect.

5 questions

Tap an answer and you’ll see straight away whether it’s right, and why.

Worksheet

2 questions, 4 marks. Write your answers on paper, then check them.

Computer modelling

Cambridge IGCSE Information & Communication Technology 0417 · 4 marks · papermunch.org

Name ______________________________ Date ______________

Give two reasons why engineers use a computer model when designing a bridge.[2]
Show answerHide answer
It is cheaper than building the bridge to test it. Dangerous conditions, such as very high winds, can be tested safely. (Also: many designs can be tried quickly.)
I got this one
Give two disadvantages of using computer models.[2]
Show answerHide answer
The results are only as accurate as the data and rules put in. A real situation may include factors that the model leaves out.
I got this one

Answers: Computer modelling

1. It is cheaper than building the bridge to test it. Dangerous conditions, such as very high winds, can be tested safely. (Also: many designs can be tried quickly.)
2. The results are only as accurate as the data and rules put in. A real situation may include factors that the model leaves out.