Nikita Boyarkin

Data → decisions. From hypothesis to ship-gate.

Data Analyst / Product Analyst
SQL Python A/B Testing Retention Segmentation

Open to Data / Product Analyst roles.

I help product teams make decisions on data: A/B tests with reproducible methodology (CUPED, AA-tests, Bonferroni, ship-gates), retention analytics, and SQL dashboards that don't lie.

4+ years at the intersection of product, data, and experimentation. Synthetic data, real methodology.

Start here CV GitHub · LinkedIn · Graph

Nikita Boyarkin
13
projects in portfolio
10
SQL cases on DuckDB
+6.24pp
KYC conversion
€716K/yr
annual fix impact

Notjustdashboardsadecisionsystem.Everymetricanswersaproductquestion,everyexperimentpassestheship-gate,anddataspeakswithonevoice.

Projects

A/B Testing Methodology Toolkit

A/B Testing Methodology Toolkit

Calibration-driven A/B testing methods, validated by simulation — SRM, CUPED, delta-method ratio metrics, alpha-spending boundaries, always-valid p-values (mSPRT), bootstrap CIs, HTE, multiple-comparison correction, novelty/primacy and switchback designs. Every module ships with an A/A null check and a power/coverage calibration.

PythonNumPy / SciPypytestuv

Impact: 15 modules, each calibrated by simulation: Type I error ≈ α, power curves, CUPED: SE shrinks by ~corr(X,Y)², Naive peeking inflates Type I error — Pocock/OBF and mSPRT keep it under control, Delta method gives the correct SE for ratio metrics (CTR, RPC) — the naive per-unit t-test is biased, End-to-end pipeline: SRM → CUPED → delta-method CTR → per-segment ATE + BH → novelty check

Product Analytics + A/B on Supabase

Product Analytics + A/B on Supabase

Full-stack product analytics platform — a Streamlit dashboard reading live Supabase Postgres through Row Level Security, plus an Edge Function ingest API and a concluded A/B experiment with SQL-computed conversion and a chi-square significance test.

PythonStreamlitSupabase (Postgres + RLS + Edge Functions)SQLsupabase-py

Impact: Full-stack: Streamlit UI + Supabase Postgres + Edge Function ingest (API-key auth), Row Level Security on every table — a user sees only their org's rows, SQL views compute funnel, cohort, MRR, DAU, channel conversion — the dashboard reshapes, it does not aggregate, A/B result in the DB: control 32.1% vs treatment 37.2%, p = 0.0034 (chi-square)

Repo is private — available on request

TaskFlow — PostHog Product Analytics Pipeline

TaskFlow — PostHog Product Analytics Pipeline

End-to-end portfolio project — instrument a SaaS product with PostHog, generate realistic traffic, and analyze the events into a funnel, cohort retention, an A/B test, revenue/LTV, and time-to-convert, all in Python.

PythonPostHogFastAPIStreamlitpandas / matplotlibpytest / ruffDocker

Impact: Typed event catalog (single source of truth) + PostHog capture/identify/group with PII scrubbing, Feature flag → onboarding A/B variant; A/B analysis with chi-square, uplift, Wilson CI + SRM check, Day-N cohort retention, time-to-convert, revenue/LTV, first-feature → upgrade conversion, The same metrics as SQL (BI / interview reference) + interactive Streamlit dashboard, CI (pytest + ruff) + Docker + render.yaml for one-click deploy

Repo is private — available on request

Product Analytics Dashboard (Streamlit)

Product Analytics Dashboard (Streamlit)

A self-contained product analytics dashboard on a synthetic SaaS dataset (8,000 users). Covers the AARRR funnel, cohort retention, revenue, and user segmentation.

PythonStreamlitpandas / NumPy

Impact: 8,000 synthetic users, Jan 2024 – Jun 2025, deterministic seed = 42, AARRR funnel: app_open → signup → activate → start_trial → subscribe with step drop-off, Cohort retention heatmap (signup month × months since signup), Revenue: MRR growth, MRR by plan, ARPU, logo churn, Segments: distributions + conversion + ARPU by segment / channel / country / device

Repo is private — available on request

Sales Calls Analytics Dashboard

Sales Calls Analytics Dashboard

Streamlit dashboard for AI sales-call analytics — a 4-step funnel (greeting → offer → meeting → qualification), step-1 leak breakdown by type, weighted contact loss, client reactions, engagement by hour and day, bot-quality defects, and drill-down into drop-off transcripts.

PythonStreamlitpandas

Impact: 16,891 synthetic calls, deterministic labeling (script markers), 4-step funnel: greeting → offer → meeting → qualification, Main leak broken down by type (silence / hang-up / refusal) + weighted contact loss, Engagement by hour and weekday — when to call, LLM labeling hook (llm_labels.csv) — the pipeline is reproducible without it

SQL Analytics Case Study

SQL Analytics Case Study

Ten end-to-end SQL case studies on a synthetic product dataset (~183k events), runnable on DuckDB with one command. Funnel, N-day retention, DAU/MAU stickiness, LTV, gaps-and-islands streaks, A/B conversion, and revenue attribution.

SQLDuckDBPythonpandas / NumPypytest

Impact: 10 self-contained SQL cases (funnel → attribution), DuckDB — no server, no credentials, one command, Regression tests with deterministic invariants per case, Synthetic deterministic data (seed=42, ~183k events)

RFM Analysis of Bank Clients

RFM Analysis of Bank Clients

RFM analysis of bank clients to segment users by Recency, Frequency, and Monetary metrics. Surfaced key customer groups, optimized marketing campaigns, and improved retention efficiency.

PythonSQLTableau

Impact: Identified high-value customer segments, Optimized marketing campaigns, Improved retention efficiency

Cohort Analysis Dashboard

Cohort Analysis Dashboard

Cohort retention and LTV analysis on synthetic data — retention curves, churn patterns, and revenue/LTV by acquisition cohort. Python pipeline (pandas + matplotlib/seaborn) plus a Tableau-ready export with CSV and Hyper extract.

Pythonpandasmatplotlib / seabornJupyter NotebookTableau (Hyper API)

Impact: Cohort retention matrix with triangular decay, ARPU / LTV by cohort with proper observation-age caveat, Tableau-ready export (CSV + .hyper extract), Reproducible seeded pipeline (seed=42)

Reporting Automation Telegram Bot

Reporting Automation Telegram Bot

A Telegram bot that automates weekly reporting and integrates with external APIs. Cuts time on routine tasks, ensures timely delivery of key metrics, and improves team communication.

Pythonaiogram / telegram-botSQLcron schedulerTableau

Impact: Cut weekly report prep from 1–2h to automated cron, KPI table + sparklines delivered on schedule, Fallback notifications on source failures, Single consolidated pipeline replacing fragmented sources

Scrolly English Speaking

Scrolly English Speaking

A scrollytelling guide for improving spoken English in workplace conversations (A2–B1) — built on Astro 6 with an MDX narrative and D3 visualizations. Content and visuals are decoupled: MDX holds the text, data modules hold section structure and viz props.

AstroTypeScriptMDXD3Tailwind v4

Impact: Scrollytelling narrative on Astro 6 + MDX, D3 visualizations (workflow, bars, calendar, checklist), Content and visuals decoupled — trusted data module, frontmatter safely merged on top, Interactive viz panels via IntersectionObserver + dark/light theme + reduced-motion, Deployed to GitHub Pages subpath, Node 22, `astro check` in CI

Digital Garden

Digital Garden

A personal digital garden and Zettelkasten published as a website with Quartz v4 — linked notes, backlinks, graph view, and atomic evergreen notes instead of chronological blog posts.

TypeScriptQuartz v4MarkdownObsidian

Impact: Linked-notes Zettelkasten with backlinks + graph view, Atomic evergreen notes over chronological posts, Quartz v4 — TypeScript-extensible, static output, Obsidian-flavored Markdown → public site

This Portfolio Site

This Portfolio Site

The portfolio you are looking at — built with Astro v5, TypeScript, and Markdown content collections. Static output, dark/light theme, RSS, sitemap, JSON-LD, and a base-path-aware URL helper for GitHub Pages.

AstroTypeScriptMarkdownCSS custom properties

Impact: Astro v5 + TypeScript + Markdown content collections, Dark/light theme with no-flash inline script, RSS, sitemap, robots, JSON-LD, OG/Twitter meta, Base-path-aware URLs for GitHub Pages subpath hosting

Project path

From hypothesis to ship-gate — the portfolio told as a sequence.

  1. Volta Neobank — Product Analytics

    Product / Data Analyst · Python · pandas / NumPy · SciPy / Statsmodels · scikit-learn · Matplotlib / Seaborn · uv + ruff

    End-to-end neobank analytics narrative — funnel, A/B test, retention, segmentation. Four sequential projects on synthetic fintech data with reproducible seeded pipelines and ship-gated statistical methodology.

    • +6.24pp KYC conversion (Z=6.35, p<0.0001), €716K/yr (48× ROI)
    • +9.2pp M3 retention, +€227K/yr incremental LTV
    Open →
  2. A/B Testing Methodology Toolkit

    Product / Data Analyst · Python · NumPy / SciPy · pytest · uv

    Calibration-driven A/B testing methods, validated by simulation — SRM, CUPED, delta-method ratio metrics, alpha-spending boundaries, always-valid p-values (mSPRT), bootstrap CIs, HTE, multiple-comparison correction, novelty/primacy and switchback designs. Every module ships with an A/A null check and a power/coverage calibration.

    • 15 modules, each calibrated by simulation: Type I error ≈ α, power curves
    • CUPED: SE shrinks by ~corr(X,Y)²
    Open →
  3. Product Analytics + A/B on Supabase

    Product / Data Analyst · Python · Streamlit · Supabase (Postgres + RLS + Edge Functions) · SQL · supabase-py

    Full-stack product analytics platform — a Streamlit dashboard reading live Supabase Postgres through Row Level Security, plus an Edge Function ingest API and a concluded A/B experiment with SQL-computed conversion and a chi-square significance test.

    • Full-stack: Streamlit UI + Supabase Postgres + Edge Function ingest (API-key auth)
    • Row Level Security on every table — a user sees only their org's rows
    Open →
  4. TaskFlow — PostHog Product Analytics Pipeline

    Product / Data Analyst · Python · PostHog · FastAPI · Streamlit · pandas / matplotlib · pytest / ruff · Docker

    End-to-end portfolio project — instrument a SaaS product with PostHog, generate realistic traffic, and analyze the events into a funnel, cohort retention, an A/B test, revenue/LTV, and time-to-convert, all in Python.

    • Typed event catalog (single source of truth) + PostHog capture/identify/group with PII scrubbing
    • Feature flag → onboarding A/B variant; A/B analysis with chi-square, uplift, Wilson CI + SRM check
    Open →
  5. Product Analytics Dashboard (Streamlit)

    Product / Data Analyst · Python · Streamlit · pandas / NumPy

    A self-contained product analytics dashboard on a synthetic SaaS dataset (8,000 users). Covers the AARRR funnel, cohort retention, revenue, and user segmentation.

    • 8,000 synthetic users, Jan 2024 – Jun 2025, deterministic seed = 42
    • AARRR funnel: app_open → signup → activate → start_trial → subscribe with step drop-off
    Open →
  6. Sales Calls Analytics Dashboard

    Product / Data Analyst · Python · Streamlit · pandas

    Streamlit dashboard for AI sales-call analytics — a 4-step funnel (greeting → offer → meeting → qualification), step-1 leak breakdown by type, weighted contact loss, client reactions, engagement by hour and day, bot-quality defects, and drill-down into drop-off transcripts.

    • 16,891 synthetic calls, deterministic labeling (script markers)
    • 4-step funnel: greeting → offer → meeting → qualification
    Open →

🎮 Arcade

Browser mini-games — including some about analytics: A/B Test (chase p < 0.05), Funnel Drop (catch users through the funnel), plus classic Snake / 2048 / Pong. Works on phone too: swipe, drag, tap.

Play →

How I can help

Concrete engagement formats — for teams that need a solved problem, not "analytics in general".

A/B methodology audit

Review of your experiment process: SRM checks, multiple-comparison correction, CUPED, ship-gates. I will find where you ship statistically-significant but business-insignificant changes.

Retention / cohort dashboard

Cohort curves, LTV decomposition, and a retention dashboard on your data. SQL + Python + BI export.

SQL review & optimization

Heavy-query review, gaps-and-islands, window functions, migration to DuckDB/ClickHouse. Runnable synthetic cases.

Segmentation & monetization

RFM or KMeans user segmentation with a per-segment strategy and incremental-revenue estimate.

Discuss →

Now

Telegram: @lofinibo →

Fresh materials

All writing →

About Me

I work at the intersection of product, data, and experimentation. My background spans customer analytics, A/B testing, dashboard design, and building data pipelines that help teams make faster decisions.

Outside of work I maintain an Obsidian knowledge base on product analytics, experiment with AI-assisted workflows, and write about practical data techniques.

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