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OCR H446 2.2.2 Heuristics: informed estimates
Part 8 of 14 · H446 2.2.2 · Computational methods
A heuristic guides which option a search explores first without promising the best answer, and H446 2.2.2 examines exactly that distinction. Maintenance scheduling and rehearsal-room allocation give students scoring rules to calculate, a weighting to change, and a clear view of what the change costs.
Students will:
- define a heuristic and explain how it orders the options a search explores
- calculate scores from a stated scoring rule and select the option it favours
- compare two route estimates under stable conditions and under rapidly changing ones
- explain how altering a weight shifts which options win, and which cases it disadvantages
- evaluate a scoring rule against both solution quality and the cost of computing it
Inside: 7 explanation cells, 1 multiple-choice question, 2 fill-in-the-blanks cells and 2 written answers. 23 marks, about 20 to 30 minutes.
Series: H446 2.2.2 · Computational methods, part 8 of 14.
Shared by Coding PathwayVerified teacher
- 12 cells
- About 30 minutes
- CC BY-SA 4.0
- Shared 31 Aug 2026
- Updated 3 Sept 2026
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The whole resource, exactly as a class sees it. Answers and marking are held back.
Heuristics: informed estimates
A maintenance planner has many possible jobs and routes. Searching every possibility may take too long, so a heuristic uses a rule or estimate to guide which option is explored first.
By the end, you will be able to
- define a heuristic and explain its role;
- calculate and interpret a simple score;
- distinguish guidance from a guaranteed exact answer;
- evaluate speed, quality and calculation-cost trade-offs.
Reactivate: an exhaustive search explores all relevant alternatives; a greedy choice commits to a locally preferred option.
Guidance, not magic
A heuristic is an informed rule or estimate used to guide search or decision-making. In a route search, an estimate of remaining distance can order which location is explored next. In scheduling, a score may combine urgency and duration.
The heuristic is valuable only if it is sufficiently informative and cheaper than the work it saves. It may find a good solution quickly without guaranteeing the optimum. In algorithms such as A*, properties of the heuristic affect whether an optimal route is guaranteed; at this level, always explain the estimate’s role, not just its definition.
Worked score
For each task, calculate score = waiting_time + 3 × urgency, then choose the largest score.
- Task A: 12 + 3×2 = 18
- Task B: 5 + 3×5 = 20 ← choose first
- Task C: 16 + 3×1 = 19
Increasing the urgency weight makes urgent tasks more influential. That may improve response to critical work but delay long-waiting low-urgency jobs. The numbers encode a policy choice and must be evaluated against the purpose.
What is the main role of a heuristic in a search?
- AProve that every returned answer is optimal
- BReplace all data with random values
- CEnsure every possible state is always explored
- DGuide the order or choice of alternatives using an informed estimate or rule
- search
- quality
- cost
- syntax
Guided comparison
Route estimate H1 uses straight-line distance. H2 uses straight-line distance plus a live congestion estimate. H2 may guide search better, but it needs current data and more computation. Compare them under two conditions: stable quiet roads, then rapidly changing congestion. Avoid saying ‘H2 is more accurate’ without stating why and what that changes.
Compare H1 and H2 as heuristics for finding a delivery route.
Discuss information required, calculation cost, guidance quality and changing conditions.
Students type their answer here.
Independent evaluation
A rehearsal scheduler scores a possible room as unused_capacity + 4 × missing_features and explores the lowest score first. Most groups need only basic equipment, but a few require specialist access features. Consider how the score guides search, why the weight matters and when the scheduler should still examine alternatives.
Evaluate the use of this heuristic when allocating rehearsal rooms.
Apply each point to capacity, missing features and the weight of 4. Reach a supported judgement.
Students type their answer here.
Closed-book checkpoint
Complete each sentence from memory. There is no answer bank and correctness is held for teacher review.
Review your understanding
Before submitting, check that you can explain the central distinction in your own words, expose the intermediate state that supports your answer and apply the method in an unfamiliar context.