Case study 01 · Cohort analysis · Customer behaviour

What makes a new customer valuable?

Personal banking was behind its plan for monthly active customers, and many new accounts never transacted or went quiet within weeks. The Head of Growth and the CMO asked me what separates the customers who stay from the ones who don't. I followed thirteen monthly onboarding cohorts to find out. The answer was smaller and earlier than anyone expected.

Role
Lead analyst, research design to recommendations
Context
Personal banking at a leading Nigerian fintech
Methods
Cohort retention, behavioural segmentation, transaction-mix analysis, cross-cohort validation
Tools
SQL (ClickHouse), Python (pandas), Excel

Situation

Monthly active customers were behind the year's plan. Many new accounts never transacted, and many more went quiet within months, each one after paying to acquire it.

Task

The Head of Growth and the CMO asked which early behaviours mark a customer who becomes valuable, so onboarding could steer new users towards them instead of winning them back later.

Action

Followed the January 2025 cohort for 13 months across five behavioural personas, repeated it on 12 more monthly cohorts, and broke each persona's activity down by transaction type.

Result

An everyday payment (airtime, data or a bill) in the first 30 days marked the customers who stayed: about 5× the retention and 4× the transactions of transfer-only customers. It shaped the onboarding rebuild in case study 02: sign-up conversion +3–4pp, new-user VAS adoption +8–9pp.

Situation and task

The year's growth plan set a target for monthly active personal-banking customers well above where the year started. By the end of the first quarter, actives were behind plan and so were sign-ups (case study 02 sets out the gap and the levers). The base itself was in reasonable shape: the share of registered customers who were active was in line with what banks usually see. The problem was at the front door. A large share of new accounts never made a single transaction, and another large group was active for a while and then went dormant. Every one of those accounts had cost money to acquire.

The Head of Growth and the CMO asked me to find out what a valuable customer actually does in their early days, so that onboarding could push new users towards it rather than relying on reactivation campaigns to win them back later.

Five behavioural personas

I took the January 2025 onboarding cohort and followed every account for thirteen months. Each customer was classified by what they had done over their life on the platform. VAS here means value-added services: everyday payments such as airtime, mobile data and bills like electricity or TV.

Retention here is strict: active users in a month divided by everyone originally onboarded in that cohort. It measures how much of the acquisition spend is still alive, not just how busy the survivors are.

Thirteen months of the January 2025 cohort, by personaRebuilt from real data
Early VAS vs transfer-only retention, month 12
Early VAS vs transfer-only transactions per active user, month 12
Early VAS vs the average non-VAS persona, cumulative revenue

Retention

share of the persona's onboarded customers active

Transactions per active user

index, transfer-only month 0 = 1

Revenue per active user

index, transfer-only month 0 = 1

Cumulative revenue per active user

running total of the revenue index

Hover any chart to read all five personas for that month; the same month is shown on all four charts. Retention is a share of everyone onboarded into the persona. Transactions and revenue are averages per active user, indexed so that transfer-only in month 0 = 1. Revenue counts fee-earning transfers and payments only, so card-only customers sit at zero by construction. Values are rebuilt from the real cohort table: retention as shares, the rest indexed, all lightly perturbed. No counts are shown.

What the cohort showed

One cohort could be a fluke, so I repeated the analysis on every monthly cohort through to January 2026, twelve more in all. The ordering of the personas, and the size of the early-VAS gap, barely moved from month to month. The newest cohorts opened a little higher, especially late VAS users, which I flagged as worth watching rather than a break in the pattern. That stability was what made the finding usable as a planning baseline rather than an interesting chart.

Does the pattern hold across thirteen monthly cohorts?Rebuilt from real data
Jan 2025highlighted cohort (hover a line)

One panel per persona, all on the same scale so the panels compare directly. Retention is the share of the persona's onboarded customers active that month; transactions and revenue are per active user, indexed so transfer-only month 0 of the January 2025 cohort = 1. Each line is one monthly onboarding cohort from January 2025 to January 2026; darker lines are more recent, and recent cohorts are shorter because they have less history. Hover a line to highlight that cohort in every panel. Lines that stack on top of each other mean the pattern is structural, not seasonal.

Everyday payments come on top, not instead

A fair worry about pushing everyday payments is cannibalisation: does an airtime purchase just replace a transfer the customer would have made anyway? Splitting each persona's monthly transactions by type answered that. Early VAS customers made about four times as many transactions a month as transfer-only customers, and more than twice as many transfers. The everyday payments came on top of the core activity, not instead of it. Once a customer buys airtime in the app, it tends to become the account they run their money through.

The revenue mix makes the same point from the other side. Mobile data was a small slice of early VAS customers' transactions but close to a quarter of their revenue, so a data purchase earns several times what a transfer does. Late VAS customers show the shift happening: they started out earning nothing from everyday payments, and by the end of the year airtime and data made up about half of their revenue.

What each persona does in a month, and where the revenue comes fromRebuilt from real data
early VAS vs transfer-only, transactions per active user per month
early VAS vs transfer-only, transfers alone
mobile data's share of early VAS transactions vs its share of their revenue

Transactions per active user per month

by type; index, transfer-only total = 1

Early VAS: share of transactions vs share of revenue

by type, months 1 to 11

January 2025 cohort, averaged over months 1 to 11 (month 0 is the part-month of onboarding). Left: monthly transactions per active user by type, indexed so transfer-only customers' total = 1. Right: the share of early VAS customers' transactions and of their revenue that each type makes up. Revenue counts fee-earning transfers and payments only, so cards carry no revenue here by construction. Values rebuilt from the real breakdown and lightly perturbed; no counts are shown.

The details that shaped the design

The second purchase is the habit

Looking at what customers did second, not just first, everyday payments jumped. Many customers who started with a transfer moved to an airtime purchase next; it was the most common path on the platform. Most top-tier users made their second everyday payment within a few days of the first. A habit forms in days, not weeks. That pointed at a reward for the second purchase, inside a short window.

Agent-referred and digital customers are different customers

Customers onboarded through the agent and referral network got a physical card as part of signing up, so card adoption looked high from day zero. That was a process step, not intent. Their first transfer came later (a trust lag), but once active they were more loyal. Digital customers churned harder early, yet the ones who stayed earned more per head. One onboarding journey for both would underserve both.

Region changes the product, not the principle

The early-VAS effect held nationally. What varied was which product led. Airtime was common everywhere, but mobile data adoption was far lower in the north than the south, so a data-first message would miss many northern users. The southern markets earned more per user but were more competitive and churned faster.

Verification tier is a revenue multiplier

Customers at the highest verification tier (KYC level) earned considerably more and retained better in nearly every persona. Higher tiers unlock higher limits and more products, so verification is not only a compliance step. It also enables value, which made it a lever worth rewarding.

Who is stuck at the lowest verification tier?

If each step up in verification tier carries more revenue per customer, the next question is where the customers stuck at the bottom actually are, because that is where upgrade nudges should go. I broke the customer base down by single year of age, onboarding channel and region. Three things stood out: the youngest customers are overwhelmingly at the lowest tier, the share at the bottom is smallest in the thirties and creeps back up after the mid-forties, and agent-referred customers are far more likely to stay at the lowest tier than digital ones at almost every age.

Share of customers at each verification tier, by ageIllustrative data
of the youngest age band still at tier 1 (this channel)
agent-referred vs digital share at tier 1, averaged over age bands

Each bar is one age band and adds up to 100%. Darkest = the lowest verification tier. Regions are Nigeria's geopolitical zones, with Lagos split out. The agent-referred gap holds in every region, though it is much narrower in the South East.

Balance-holders need a different offer

A minority of dormant accounts held meaningful balances without transacting. For them, a payments cashback is the wrong tool: their value is in deposits. I split them out as a separate savings opportunity.

What happened next

I took these findings, together with the activation-speed analysis in case study 02, to the Head of Growth and the CMO. The company rebuilt its onboarding flow to steer new users towards an everyday payment early. Measured before and after the change, the share of sign-ups that went on to open an account rose by 3–4 percentage points and VAS adoption among new users rose by 8–9 points. The work also prompted a follow-up customer research study (several hundred customers, run by a colleague), which independently reached the same conclusions: habits form early, and staged rewards for a second purchase are the lever.

How I did it

  1. Define the outcome. Strict cohort retention (active this month over everyone onboarded) plus volume and revenue per active user, always read next to retention so a shrinking-but-busy cohort could not look healthy.
  2. Classify behaviour. Lifetime transaction history rolled up into five mutually exclusive personas, with the 30-day line separating early from late VAS.
  3. Replicate. The same queries run on each monthly cohort across a year, comparing persona curves and gaps rather than trusting one month.
  4. Break down the mix. Each persona's monthly transactions and revenue split by type (transfer, card, airtime, data, bills), to test whether everyday payments replace core activity or add to it.
  5. Sequence analysis. First-to-second transaction transitions and the days between them, to find the habit-forming step.
  6. Cut by context. Region, verification tier, onboarding channel and balance behaviour, to find where one national answer would break; then verification tier by single year of age to see who is stuck at the bottom.

Caveats and what I'd do differently

Skills shown

Cohort analysisBehavioural segmentationTransaction-mix analysisCross-cohort validationRegional and channel cutsInsight to product recommendation