# Testing One-Click Saved Card Payment at Checkout

Page: https://alidemirbas.com.tr/en/lab/ab-test-library/tests/testing-one-click-saved-card-payment-at-checkout

## Hypothesis

If eligible users can pick their saved card instead of typing their details again, typing errors and drop-off at the card fields may fall. Even with required verification left in place, the payment completion rate could improve.

## When to run this test

Drop-off concentrated in the card fields in form analytics, entry errors on mobile, or support tickets about retyping card details tell you that users with a saved card struggle at this step. Given the option, eligible users should pick the saved card and finish the payment step faster. If losses cluster around payment errors, declines or the provider, look at that technical side first; adding a new option will not resolve it. Before launch, make sure the saved card is never preselected without the user's consent, and keep that rule fixed for the whole test.

## Primary metric

**Payment completion rate**: Compare orders placed by assigned checkout visitors who are eligible for saved-card checkout.

## Other metrics

- **Payment method selection rate**: Track which payment method visitors choose.
- **Payment-step completion time**: Check whether the payment step takes less time.
- **Payment error and decline rate**: Track errors and declines during payment attempts.
- **Post-purchase cancellation rate**: Compare order cancellations over the same follow-up period in both arms.

## What to check before and during the test

- **Payment option**: Offer saved-card checkout to eligible users who have a saved card; keep manual entry available.
- **Keep constant**: Keep manual card fields, payment provider, validation and checkout flow unchanged.
- **Selection**: Track preference for saved-card checkout versus manual entry.
- **Device**: Review mobile and desktop separately.
- **Separate tests**: Do not include option placement, default selection or provider changes in this test.

## What to watch when reading the result

- Read any gain in payment completion rate alongside the payment error and decline rate and post-purchase cancellations, using the same follow-up period in both arms. Higher completion that comes with more declines or cancellations does not justify a rollout.
- Analyze only the eligible users assigned to the experiment, and do not generalize to users without a saved card; including them dilutes the effect. Payment method selection rate shows whether the difference really comes from people choosing the saved card; look at the device split too.
- Eligible users are only part of checkout traffic, so the sample may be smaller than you expect. An unclear gap from a small eligible group does not mean the option fails; assess how reliable the gap is with the [A/B test significance calculator](https://alidemirbas.com.tr/en/calculators/ab-test).
- In the variant, check that the saved-card option does not crowd the mobile screen and that no oversized callout hides other parts of the page. If either problem shows up, do not credit the completion gap to the saved-card option alone.

## Frequently Asked Questions

### Does saved-card checkout complete every payment in one click?

No. Required authentication remains. Eligible users can avoid re-entering card details, but manual entry is still available. Use payment completion as the primary outcome.

### Which visitors should be included in the analysis?

Use the predefined eligible payment visitors assigned to the experiment. Users without a saved card may receive no meaningful difference. Define eligibility before exposure rather than selecting users who later choose the feature.

### Which risks matter if payment completion increases?

Monitor payment errors, declines and subsequent order cancellations using equal follow-up windows. Payment-method selection explains whether eligible users actually choose the saved card.

### Is making the saved card the default a separate A/B test?

Yes. Adding an option and making it the default are different changes. Define the initial selection rule before launch and keep it consistent. Preserve manual entry and required payment checks.