To be marked well you have to describe a system precisely: its elements, its connections, its boundary, its purpose and its feedback. Five words, and the last three are where the marks are.
The five words built up on one system, so each arrives attached to something real.
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| Word | What it means | Why it earns marks |
|---|---|---|
| Elements | The parts you can point at | Sets up everything else |
| Connections | What passes between them | Most answers leave this out |
| Boundary | What counts as inside | Decides what may change |
| Purpose | What it reliably produces | Not what it claims to do |
| Feedback | Output returning as input | Explains why it drifts |
The boundary sets the answer: Whatever you leave outside the boundary is treated as fixed. Put the company's business model outside and no solution can touch it — which is how an honest analysis reaches a useless conclusion.
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A system's purpose is read from its behaviour, not from its mission statement. If it reliably produces an outcome, that outcome is a purpose whether or not anybody chose it.
Real-world examples you can name
YouTube's recommendation system — deep-learning system described 2016; borderline-content changes from January 2019
A ranking system that predicts what a viewer will watch next, which the company has said drives the majority of watch time. After criticism that it led viewers towards ever more extreme material, the company began demoting 'borderline' content rather than removing it.
Who it affected: Roughly two billion monthly viewers, and creators whose income depends on the ranking.
COMPAS recidivism scoring — ProPublica investigation May 2016
A commercial risk-scoring tool used in some US courts to estimate how likely a defendant was to reoffend. Journalists found that among people who did not go on to reoffend, Black defendants were roughly twice as likely as white defendants to have been labelled high risk. The company disputed the measure of fairness used, and the argument that followed showed that competing definitions of a fair algorithm cannot all be satisfied at once.
Who it affected: Defendants whose bail and sentencing decisions were informed by the score.
How to use this in an answer: Write “the stated purpose is X; the purpose you can read from its behaviour is Y.” It is a serious claim, it is usually true, and it is exactly the analysis part c wants.
How this is tested — Paper 1 part b frequently hands you a system and asks you to describe how it works. It comes up two ways:
Paper 1 — structured question
- Part b: explain how a described system operates
- Part c: evaluate a system, which needs its purpose named
Paper 2 — source-based question
- Q2: explain a system a source describes
- HL Paper 3: analyse the system in the statement
The trap: elements only: A list of parts scores at the bottom. What passes between them, and what returns, is where the analysis lives.
Explain how feedback can cause a recommendation system to change over time.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
Analyse a risk-scoring system used in a court, identifying its purpose.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.