---
artifact: experiment-results
version: "1.0"
created: 2026-01-14
status: complete
context: E-commerce checkout optimization A/B test
---

# Experiment Results: One-Page Checkout vs. Multi-Step Checkout

## Summary

| Attribute | Value |
|-----------|-------|
| **Experiment ID** | EXP-2026-001 |
| **Experiment Name** | One-Page Checkout |
| **Status** | Completed |
| **Duration** | December 15, 2025 to January 10, 2026 (26 days) |
| **Traffic Allocation** | 50% control / 50% treatment |
| **Total Sample Size** | 47,832 users (23,891 control, 23,941 treatment) |
| **Owner** | Sarah Martinez, Product Manager |
| **Design Doc** | EXP-2026-001 Design (internal link) |

---

## Hypothesis Recap

**Original Hypothesis:**

> We believed that consolidating our 3-step checkout into a single page with accordion sections would increase checkout conversion rate because reducing perceived complexity and eliminating page loads would reduce drop-off at each step.

**Success Criteria:**

- Primary metric: Checkout conversion rate improves by at least 3%
- Statistical significance: p < 0.05 (two-tailed)
- Minimum sample size: 20,000 users per variant

---

## Results

### Primary Metric: Checkout Conversion Rate

| Variant | Value | Sample Size | Confidence Interval (95%) |
|---------|-------|-------------|---------------------------|
| Control (3-step) | 62.4% | 23,891 | 61.8% - 63.0% |
| Treatment (1-page) | 65.6% | 23,941 | 65.0% - 66.2% |

**Observed Difference:** +3.2 percentage points (+5.1% relative improvement)

**Statistical Significance:**
- p-value: 0.0003
- Confidence level: 95%
- Statistically significant: **Yes**

**Interpretation:**

The one-page checkout significantly outperformed the 3-step checkout. We can be 95% confident that the true improvement is between 1.8% and 4.6% (absolute). The result exceeds our 3% threshold for success.

---

### Secondary Metrics

| Metric | Control | Treatment | Difference | Significant? |
|--------|---------|-----------|------------|--------------|
| Cart-to-checkout start | 78.2% | 79.1% | +0.9% | No (p=0.12) |
| Average order value | $87.42 | $86.91 | -0.6% | No (p=0.34) |
| Items per order | 2.31 | 2.28 | -1.3% | No (p=0.22) |
| Time in checkout | 4.2 min | 3.1 min | -26.2% | Yes (p<0.001) |
| Payment errors | 2.1% | 1.8% | -14.3% | Yes (p=0.03) |

### Guardrail Metrics

| Metric | Control | Treatment | Threshold | Status |
|--------|---------|-----------|-----------|--------|
| Return rate (7-day) | 8.2% | 8.4% | No increase > 1% | **Pass** |
| Customer support tickets | 0.9% | 0.7% | No increase > 0.5% | **Pass** |
| Payment failure rate | 3.4% | 3.2% | No increase > 0.5% | **Pass** |

---

## Segment Analysis

### By Device Type

| Segment | Control | Treatment | Difference | Significant? |
|---------|---------|-----------|------------|--------------|
| Desktop | 68.3% | 69.5% | +1.2% | No (p=0.18) |
| Mobile | 54.2% | 59.3% | +5.1% | **Yes** (p<0.001) |
| Tablet | 61.7% | 64.1% | +2.4% | No (p=0.09) |

### By Customer Type

| Segment | Control | Treatment | Difference | Significant? |
|---------|---------|-----------|------------|--------------|
| New customers | 51.8% | 57.2% | +5.4% | **Yes** (p<0.001) |
| Returning customers | 71.3% | 72.1% | +0.8% | No (p=0.28) |

### By Cart Value

| Segment | Control | Treatment | Difference | Significant? |
|---------|---------|-----------|------------|--------------|
| < $50 | 65.4% | 68.9% | +3.5% | **Yes** (p=0.008) |
| $50-$100 | 62.1% | 65.2% | +3.1% | **Yes** (p=0.02) |
| > $100 | 58.7% | 61.4% | +2.7% | No (p=0.07) |

### Segment Insights

The treatment effect was **strongest on mobile devices** (+5.1% vs +1.2% desktop) and for **new customers** (+5.4% vs +0.8% returning). This makes sense: new customers benefit most from reduced cognitive load, and mobile users benefit most from fewer page loads and scrolling.

Returning customers showed minimal improvement, likely because they've already learned the existing checkout flow.

---

## Visualization

### Conversion Rate Over Time

The treatment consistently outperformed control throughout the experiment period. No significant interaction with time was observed (e.g., novelty effect wearing off).

```
Conversion Rate by Day
       70% |
           |    ████████████████████████  (Treatment)
       65% |████████████████████████████
           |
       60% |████████████████████████████  (Control)
           |
       55% |________________________________
              Dec 15                Jan 10
```

### Funnel Drop-off Comparison

| Step | Control Drop-off | Treatment Drop-off | Improvement |
|------|------------------|-------------------|-------------|
| Cart → Checkout | 21.8% | 20.9% | +0.9% |
| Shipping info | 8.4% | N/A (combined) | . |
| Payment info | 5.2% | N/A (combined) | . |
| Review → Purchase | 4.1% | 3.5% | +0.6% |
| **Total checkout drop** | 37.6% | 34.4% | **+3.2%** |

---

## Learnings

### What We Learned

1. **Reducing page loads matters more than expected**
   The 26% reduction in checkout time suggests page load latency was a bigger friction point than the form complexity itself. Users were abandoning during transitions between steps.

2. **Mobile optimization is high-leverage**
   Mobile users saw 4x the improvement of desktop users. Our multi-step checkout was particularly problematic on smaller screens with more scrolling and tapping between pages.

3. **New user experience is critical**
   New customers showed 5.4% improvement vs 0.8% for returning customers. First-time checkout experience has outsized impact on conversion; returning customers have already overcome the learning curve.

4. **Form length matters less than perceived progress**
   The one-page design actually shows MORE fields at once, but the accordion UI creates a sense of progress and control. Perception matters more than raw field count.

### Surprising Findings

- **Payment errors decreased by 14%:** We didn't expect this. Hypothesis: single-page reduces context-switching errors where users forget information between steps.
- **No impact on AOV or items per order:** We worried that faster checkout might mean less consideration, leading to smaller orders. This didn't materialize.

### What We Still Don't Know

- Will the mobile improvement persist on different device types (older phones, low-bandwidth connections)?
- Is there a specific accordion section that causes the most friction? (We didn't instrument that level of detail)
- How does this interact with guest checkout vs. account checkout?

---

## Recommendation

### Decision: Ship to 100%

**Rationale:**

The experiment delivered a clear, statistically significant improvement that exceeded our success threshold. The +3.2% lift in checkout conversion represents approximately $840K in additional annual revenue at current traffic levels. No guardrail metrics were violated, and the improvement was consistent across the experiment duration.

The segment analysis reveals even higher impact on mobile and new customers.our strategic growth priorities.

### Shipping Plan

- [ ] Merge feature branch to main (Eng: Chen, by Jan 17)
- [ ] Update checkout analytics events for new flow (Eng: Chen, by Jan 17)
- [ ] Remove experiment infrastructure and flags (Eng: Chen, by Jan 20)
- [ ] Update help center documentation (Support: Lisa, by Jan 22)
- [ ] Communicate change to CS team (PM: Sarah, by Jan 17)
- [ ] Monitor conversion rate daily for 2 weeks post-launch (PM: Sarah, ongoing)

### Metrics to Continue Monitoring

- Checkout conversion rate (daily for 2 weeks, then weekly)
- Mobile vs. desktop conversion gap
- Payment error rate
- Customer support ticket volume related to checkout

---

## Next Steps

| Action | Owner | Due Date |
|--------|-------|----------|
| Ship to 100% traffic | Chen (Eng) | Jan 17 |
| Update analytics events | Chen (Eng) | Jan 17 |
| Remove experiment flags | Chen (Eng) | Jan 20 |
| Update help documentation | Lisa (Support) | Jan 22 |
| Post-launch monitoring report | Sarah (PM) | Jan 31 |
| Plan follow-up: guest checkout optimization | Sarah (PM) | Feb 1 |

---

## Appendix

### Raw Data

- Experiment Dashboard (Looker link)
- Raw data export (CSV link)
- Statistical analysis notebook (analysis link)

### Statistical Methodology

- **Test type:** Two-proportion z-test for primary metric
- **Multiple comparison correction:** Benjamini-Hochberg for segment analysis
- **Power calculation:** 80% power to detect 3% lift at α=0.05 required 18,500 per variant
- **Sequential analysis:** Not used; experiment ran to planned end date

### Known Issues

- **Dec 24-26 excluded:** Holiday traffic anomaly removed from analysis (both variants affected equally)
- **Bot traffic:** Standard bot filters applied; no unusual activity detected
- **One variant had 0.2% more iOS traffic:** Not statistically significant; analysis not adjusted

---

*Results documented on January 14, 2026. Full rollout completed January 20, 2026.*
