computer science

Goal seeking

Goal seeking is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Goal seeking rather than just read about it. In short: In computing, goal seeking is the ability to calculate backward to obtain an input that would result in a given output. This can also be called what-if analysis or backsolving.

Key takeaways

Goal seeking belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Goal seeking to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Goal seeking from memory before moving on to harder problems.

Reference excerpt

In computing, goal seeking is the ability to calculate backward to obtain an input that would result in a given output. This can also be called what-if analysis or backsolving. It can either be attempted through trial and improvement or more logical means. Basic goal seeking functionality is built into most modern spreadsheet packages such as Microsoft Excel. According to O'Brien and Marakas, optimization analysis is a more complex extension of goal-seeking analysis. Instead of setting a specific target value for a variable, the goal is to find the optimum value for one or more target variables, given certain constraints. Then one or more other variables are changed repeatedly, subject to the specified constraints, until you discover the best values for the target variables.

Examples Suppose a family wanted to take out the biggest loan that they could afford to pay for. If they set aside $500 a month, the goal-seeking program would try to work out how big a loan the family could afford to take out. Even using simple trial and improvement, a computer could quickly determine that they could not afford a $50,000 loan, but could afford a $48,000 loan. It would then repeat the process until it had reached a figure such as $48,476.34, which would give them a monthly repayment as close to $500 as possible, without exceeding it. A more efficient method, especially on more complicated calculations, would be for the program to logically work through the argument. By drawing up a simple equation, the program could come to the conclusion that the output equalled one ninety-sixth of the input, and could then multiply the output (or goal) by ninety-six to find the necessary input.

See also Global optimization Goal programming

References

Worked examples

Example 1 — a first encounter with Goal seeking

Start with the simplest possible case. Write down what Goal seeking claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Goal seeking before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Goal seeking ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Goal seeking

In research: Goal seeking appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Goal seeking in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Goal seeking is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer programming stubs, Computing terminology, Goal, so understanding it makes those chapters shorter.
In everyday life: Look for Goal seeking outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Goal seeking in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Goal seeking means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Goal seeking out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Goal seeking in simple terms?

In computing, goal seeking is the ability to calculate backward to obtain an input that would result in a given output. This can also be called what-if analysis or backsolving.

Why does Goal seeking matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Goal seeking?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Goal seeking.