Vanguard, a global investment management leader, recently launched a digital redesign of its customer onboarding experience. To assess the true impact of this redesign, the company conducted an A/B test.
Users were randomly assigned to either the control group (original user journey) or the treatment group (newly redesigned flow). The objective:
Measure if the redesign leads to a higher funnel completion rate, fewer drop-offs, and better user experience.
Note
This project simulates a real-life product experiment. It was developed during a Data Analysis Bootcamp to replicate decision-making scenarios based on real A/B testing data.
📦 Dataset Overview
The dataset consists of user navigation events throughout the onboarding funnel:
- user_id: Unique identifier per user.
- group: A/B group label – control or treatment.
- step: Funnel step (e.g., step_1, step_2, ..., confirm).
- timestamp: Timestamp of the event.
- Derived fields (created in preprocessing):
- time_diff: Time difference between steps.
- final_step: Last recorded step per user.
- error_flags: Indicators for anomalies.
🧹 Data Cleaning & Wrangling
To ensure valid insights, we applied rigorous data preprocessing steps:
- Chronologically sorted user steps.
- Removed sessions with:
- Repeated steps (e.g., multiple step_2s).
- Backward jumps (e.g., step_3 to step_1).
- Zero-second step transitions.
- Labeled sessions that did not end in confirm as abandonments.
- Engineered features for:
- Time spent per step.
- Funnel depth reached.
- Navigation consistency.
These cleaning rules were based on domain assumptions. In a production setting, more session metadata and UX feedback would further guide this logic.
📊 Exploratory Data Analysis
The EDA compared control vs. treatment groups on multiple dimensions:
- Completion Rate – % of users reaching the confirm step.
- Drop-off Points – Common exit steps.
- Navigation Errors – Frequency of repeated or reversed steps.
- Time Metrics – Total and per-step time comparisons.
Key visualizations:
- Funnel diagrams by group
- Step-wise conversion rates
- Session length distributions
🧪 Hypothesis Testing
We ran statistical tests to validate whether differences observed were statistically significant:
- ✅ Z-test for proportions (completion rate comparison).
- ✅ T-test / Mann-Whitney U test (time differences).
- ✅ Chi-squared test (distribution of final steps and errors).
- ✅ Sanity checks for group balance and random assignment.
Assumptions tested:
- Normality (Shapiro-Wilk, histograms).
- Equal variances (Levene's test).
Statistical significance ≠ business impact. All insights were contextualized with user experience and operational considerations.
📈 Key Insights
- ✅ Higher completion rate in the treatment group (statistically significant).
- 🔄 Fewer navigation errors post-redesign, especially backward transitions.
- ⏱️ Time efficiency slightly improved but not statistically conclusive.
- 🧩 Users followed a more linear path in the redesigned flow.
🧭 Recommendations
- ✅ Roll out the redesign to the broader user base.
- 📊 Monitor funnel metrics continuously to detect regressions.
- 🔬 Run additional segmented tests (e.g., new vs. returning users).
- 🧠 Gather qualitative UX insights (e.g., via surveys, heatmaps).
- ⚙️ Improve experiment design with longer run times and controlled traffic splits.
🧑🏫 Educational Context
This analysis was developed as part of a Data Analytics Bootcamp.
It reflects industry-standard approaches to experimentation, data cleaning, and interpretation of A/B tests within digital products.
As part of this project, we built an interactive web application using Streamlit to visualize key insights from the A/B test, including:
- Funnel completion rate comparisons
- Drop-off analysis by step
- KPIs and error rates
- Demographic exploration
You can explore the full dashboard here:
👉 Launch the Streamlit App
ℹ️ Best viewed on desktop for full dashboard interaction.