Stephen O.

Key Skills

Software

Appen

Scale AI

Lionbridge

Top Subject Matter

Large language model (LLM) training

safety and policy evaluation

Rlhf. Domain Expertise

Top Data Types

Text

Image

Audio

Document

Top Task Types

RLHF

Segmentation

Transcription

Freelancer Overview

Senior Data Annotation Specialist (Remote Contract) | Appen. Brings 6+ years of professional experience across legal operations, contract review, compliance, and structured analysis. Core strengths include Appen, Scale AI, and Lionbridge. Education includes Bachelor of Information Technology, University of Nairobi (2024) and Google Data Analytics Professional Certificate, Coursera (2025). AI-training focus includes data types such as Text, Image, and Audio and labeling workflows including RLHF, Segmentation, and Entity (NER).

Labeling Experience

Senior Data Annotation Specialist (Remote Contract) | Appen

AppenTextRLHF

Served as a Senior Data Annotation Specialist performing RLHF labeling and evaluations for LLM training. Worked on ranking model responses, writing ideal responses, and flagging harmful or policy-violating content according to client safety rubrics. Ensured consistent scoring outcomes through calibration and guideline updates while meeting high throughput requirements. • Labeled prompt-response pairs for helpfulness, harmlessness, honesty, and factual accuracy. • Performed response ranking, rating, and policy-violation identification. • Maintained inter-annotator agreement (IAA) of 96%+ across projects. • Conducted weekly calibration to apply updated RLHF guidelines without productivity drops.

2023 - Present

Data Annotation Analyst (Remote Contract) | Scale AI

Scale AIText

Performed text annotation for conversational AI datasets including dialogue understanding and entity-style extraction tasks. Labeled intent classes and dialogue acts, and applied coreference resolution labeling to support conversational modeling. Evaluated chatbot response quality using scoring rubrics covering coherence, relevance, tone, safety, and instruction-following accuracy. • Labeled intent classification and dialogue act tagging for conversational AI. • Completed coreference resolution annotations for dialogue context linking. • Rated chatbot outputs for coherence, relevance, tone, safety, and instruction following. • Documented edge cases and ambiguous scenarios to improve annotation guidelines.

2023 - 2024

Data Annotation Analyst (Remote Contract) | Scale AI

Scale AIImageSegmentation

Labeled computer vision training datasets for autonomous vehicle and retail imagery using segmentation and geometric annotation types. Applied detailed labeling instructions to produce bounding boxes, polygon segmentation, keypoints, and semantic labels for model training. Validated outputs by evaluating quality against rubrics and documenting edge cases for guideline improvements. • Produced bounding boxes, polygon segmentation, keypoint annotations, and semantic labels. • Flagged ambiguous scenarios and contributed to guideline clarifications adopted by the project. • Achieved a 98% task acceptance rate and ranked in the top 5% on the platform. • Reduced rework by identifying systematic annotation errors with QA leads.

2023 - 2024

Freelance Data Labeler & Transcriptionist | Lionbridge AI / Remotasks

LionbridgeAudioTranscription

Freelanced as a data labeler and transcriptionist completing multilingual audio transcription and speech annotation tasks. Produced clean verbatim and non-verbatim transcripts with speaker diarization support to support voice assistant training. Maintained high accuracy verified through QA review processes while working independently across multiple client projects. • Transcribed and annotated speech data for voice assistant training. • Achieved accuracy rates above 97% per QA review teams. • Supported multilingual transcription in English and Swahili datasets. • Maintained consistent daily productivity with minimal supervision.

2021 - 2023

Education

Work History