Senior Data Scientist (NYC)

BoldVoice (YC S21) is an AI-powered communication coach that helps non-native English speakers improve pronunciation, clarity, and confidence. We're looking for our first Data Scientist to own how BoldVoice measures itself and decides what to build next. This is not a reporting role: you will define what 'working' means for a feature, design and analyze experiments, and find the next thing worth building. You will sit at the intersection of product, growth, and the speech ML team, and your analyses will directly change the roadmap.

Responsibilities

Own experimentation end to end, including A/B test design, metric selection, statistical analysis, and shipping decisions; Build and own the metric layer (activation, trial start, trial to paid conversion, retention curves, LTV, learning outcomes); Run deep dives that change the roadmap; Turn behavioral and speech-scoring data into models (churn and conversion propensity, lesson recommendation, learning path personalization); Partner with growth on paid acquisition measurement (CAC, payback, incrementality, marketing spend allocation); Work with the ML team to measure speech model quality across accents and model impact on user outcomes; Make data self-serve for PMs, designers, and engineers

Requirements

At least 5 years in data science or product analytics, ideally at a consumer subscription app or a fast-moving startup; Deep experimentation experience: power analysis, variance reduction techniques like CUPED, handling multiple comparisons, and recognizing when a clean A/B test isn't possible; Strong SQL and Python (pandas, scikit-learn, statsmodels or equivalent) with experience working directly against a production database; Fluency with the consumer subscription funnel: install to trial to paid, cohort retention, LTV, and paid acquisition measurement; Experience with product analytics and experimentation tooling (Mixpanel and GrowthBook on PostgreSQL); Up to date with latest developments in LLM tools like Claude Code, Cursor, Codex or similar; Work in person at the downtown NYC office at least 3 days a week; Strong statistical judgment

Nice to have

Causal inference beyond A/B testing; Exposure to speech or audio ML evaluation; Experience measuring learning outcomes in education products

Benefits

Salary and generous stock options; Fully paid health, vision, and dental insurance; 401K program; Relocation assistance to NYC; Access to exclusive startup events, conferences and networks