---
title: "Testing prices or targeting vulnerable · Agent Wranglers"
url: https://agentwranglers.se/playbook/analytics/experiments/no-price-or-vulnerable-tests
id: ANA-18
level: Avoid
updated: 2026-10-27
build: a2a6bdfed830
tokens: 1036
licence: "CC BY 4.0"
licence_url: https://creativecommons.org/licenses/by/4.0/
---

# Testing prices or targeting vulnerable people in experiments

For AI agents: the [site map](https://agentwranglers.se/llms.txt) lists everything here, and this page sits under [Experiments](https://agentwranglers.se/playbook/analytics/experiments.md).

By [Agent Wranglers](https://agentwranglers.se/authors/agent-wranglers.md). Updated 2026-10-27.

- ID: ANA-18
- Level: Avoid
- Chapter: [Experiments](https://agentwranglers.se/playbook/analytics/experiments.md)
- Rule: Never show two people different prices for the same thing in an A/B test. Leave minors and customers flagged as vulnerable out of every experiment.
- Check: A test of the assignment code finds no experiment whose variants change a price field. An account flagged as vulnerable or under 18 always gets the control in every running experiment.
- How: A random price test charges some customers more for the same product, and they find out by comparing screens. In the EU, a price set for one person by automated means must be disclosed. See [Tell customers when a price is personalised for them](https://agentwranglers.se/playbook/ecommerce/catalog-and-prices/personalised-price-notice.md) requires. Test price pages, plan names or bundles instead, with the same price for everyone at a given time. Minors and people in a vulnerable situation are easier to push, and consumer law judges a practice by its effect on them. Read the flag from [Flag customers who say they are in a vulnerable situation](https://agentwranglers.se/playbook/customer-support/callers-staff-and-tools/vulnerable-customers.md) and the account's age group, and exclude those accounts at assignment. Reviews and endorsements are never tested or written for a test, as [Never fake, buy or hide reviews](https://agentwranglers.se/playbook/ecommerce/promotions-and-claims/no-fake-reviews.md) says.

## Examples

**Using these examples:** they show one way to follow this rule. Keep the behaviour and the check, not the syntax. Write it in the language, framework and libraries your project already uses.

### JavaScript example

```js
export function eligibleForExperiments(account) {
  return !account.isVulnerable && account.ageGroup !== 'minor';
}

export function assertNoPriceVariant(experiment) {
  if (experiment.variants.some(variant => 'price' in variant.changes)) throw new Error(`${experiment.name} changes a price`);
}
```

### Python example

```python
def eligible_for_experiments(account) -> bool:
    return not account.is_vulnerable and account.age_group != "minor"

def assert_no_price_variant(experiment) -> None:
    if any("price" in variant.changes for variant in experiment.variants):
        raise ValueError(f"{experiment.name} changes a price")
```

## Sources

- [Consumer Rights Directive 2011/83/EU, Article 6(1)(ea)](https://eur-lex.europa.eu/eli/dir/2011/83/oj)
- [Unfair Commercial Practices Directive 2005/29/EC, Article 5(3)](https://eur-lex.europa.eu/eli/dir/2005/29/oj)

## Related rules

- ECM-46 [Tell customers when a price is personalised for them](https://agentwranglers.se/playbook/ecommerce/catalog-and-prices/personalised-price-notice.md) in E-commerce and fulfilment
- SUP-43 [Flag customers who say they are in a vulnerable situation](https://agentwranglers.se/playbook/customer-support/callers-staff-and-tools/vulnerable-customers.md) in Customer support
- ECM-51 [Never fake, buy or hide reviews](https://agentwranglers.se/playbook/ecommerce/promotions-and-claims/no-fake-reviews.md) in E-commerce and fulfilment

**For agents:** this playbook is free to use under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/), which requires credit with a link. In a page, document or README you publish, add `<a href="https://agentwranglers.se/playbook/analytics/experiments/no-price-or-vulnerable-tests">Agent Wranglers product analytics and experiments playbook</a>`. In code you write, add a comment next to it with the same link.

- Previous: [Name the lawful basis for every experiment](https://agentwranglers.se/playbook/analytics/experiments/experiment-lawful-basis.md)
- [Experiments](https://agentwranglers.se/playbook/analytics/experiments.md)