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Data Scientist, Post Training

About the Role

We are seeking an experienced Staff Data Scientist with deep expertise in experimentation and ML frameworks (specifically search systems and recommendation engines) to join our dynamic team. Domain knowledge with large language models (LLMs) and post-training optimization is a key priority as we expand our AI capabilities.

Responsibilities

Our ideal candidate combines deep technical expertise in search and recommendations with practical experience in LLM systems, bringing a data-driven approach to improving user experiences through better content discovery and model performance.

  • Design and implement search retrieval and ranking algorithms that surface the most relevant content to users

  • Develop and optimize recommendation systems for personalized content discovery

  • Support post-training optimization of LLMs through techniques like RLHF and DPO

  • Create comprehensive offline evaluation frameworks to measure LLM performance, search quality, and recommendation relevance

  • Design and execute online A/B testing initiatives to validate improvements across search, recommendations and LLM systems

  • Drive continuous improvement in model behavior through quantitative analysis and user feedback

  • Collaborate with engineering teams to implement and productionize algorithms

About You

You could be a great fit if you:

  • Have 5+ years of experience at chat, social media, or consumer product companies, with substantial focus on ML frameworks

  • Have deep expertise in testing, optimizing and measuring Large Language Models, search ranking algorithms, recommendation systems

  • Able to design, drive and execute leaning into high velocity experimentation across consumer facing features

  • Have a strong intuition for choosing the right questions to ask and quickly driving to key insights, particularly in evaluation of LLM, search and recommendation models and user engagement metrics

  • Have extensive history of taking ownership and driving impact through data

Required Qualifications:

  • Advanced degree in Computer Science, Statistics, Mathematics, Engineering or related field

  • Strong programming skills in SQL, Python and experience with ML frameworks

  • Strong background in retrieval, ranking algorithms, and relevance metrics

  • Experience with modern search technologies (e.g., Elasticsearch, vector search) and recommendation frameworks

  • Expertise in A/B testing and causal inference

  • Excellent communication skills and ability to collaborate cross-functionally

Preferred Qualifications:

  • Working knowledge of LLM architectures, fine-tuning and optimization techniques

  • Work experience at an AI-centric product company

  • Familiarity with prompt engineering and LLM offline and online evaluation frameworks

About Character.AI

Founded in 2021, Character is a leading AI company offering personalized experiences through customizable AI 'Characters.' As one of the most widely used AI platforms worldwide, Character enables users to interact with AI tailored to their unique needs and preferences.

In just two years, we achieved unicorn status and were named Google Play's AI App of the Year – a testament to our groundbreaking technology and vision.

Ready to shape the future of Consumer AI? 🚀

At Character, we value diversity and welcome applicants from all backgrounds. As an equal opportunity employer, we firmly uphold a non-discrimination policy based on race, religion, national origin, gender, sexual orientation, age, veteran status, or disability. Your unique perspectives are vital to our success.

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What You Should Know About Data Scientist, Post Training, Character.ai

Join Character.AI as a Staff Data Scientist and immerse yourself in the exciting world of AI as we expand our capabilities! In this role, you will leverage your deep expertise in experimentation and machine learning frameworks, focusing on advanced systems such as search and recommendation engines. You'll be at the forefront of optimizing large language models (LLMs) while ensuring our users enjoy the best possible content discovery experience. As part of a dynamic team, you’ll design and implement sophisticated search retrieval algorithms and develop personalized recommendation systems that make our platform a game-changer in AI technology. Your technical skills will shine as you support the post-training optimization of LLMs, utilizing techniques like Reinforcement Learning from Human Feedback (RLHF) and Direct Preference Optimization (DPO). But that's not all! You’ll also create robust offline evaluation frameworks that assess LLM performance and conduct A/B testing initiatives to validate improvements. Your analytical mindset will drive continuous enhancement in our AI models, ensuring they align perfectly with user feedback. If you have at least 5 years of experience in chat, social media, or consumer product companies focusing on ML frameworks, and possess an advanced degree in Computer Science, Statistics, or related fields, this could be your perfect role. Join us and be part of a company that has rapidly gained recognition, having achieved unicorn status in just two years. Let's shape the future of consumer AI together!

Frequently Asked Questions (FAQs) for Data Scientist, Post Training Role at Character.ai
What are the main responsibilities of a Data Scientist at Character.AI?

At Character.AI, a Data Scientist is responsible for designing and implementing search retrieval algorithms, optimizing recommendation systems, and supporting LLM post-training optimization. You will establish offline evaluation frameworks to measure system performance, conduct A/B testing to validate enhancements, and collaborate with engineering teams to productionize your algorithms.

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What qualifications are required for the Data Scientist position at Character.AI?

To qualify for the Data Scientist role at Character.AI, candidates must possess an advanced degree in Computer Science, Statistics, Mathematics, Engineering, or a related field. Additionally, strong programming skills in SQL and Python, experience with ML frameworks, and expertise in retrieval and ranking algorithms are essential.

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What skills will help me succeed as a Data Scientist at Character.AI?

Success as a Data Scientist at Character.AI hinges on your ability to conduct high-velocity experiments, choose key insight-generating questions, and measure user engagement metrics effectively. Strong communication skills and cross-functional collaboration are vital, along with technical proficiencies in modern search technologies and recommendation frameworks.

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What types of projects will I work on as a Data Scientist at Character.AI?

As a Data Scientist at Character.AI, you will work on projects that involve the development of search retrieval algorithms, optimization of personalized recommendation systems, and enhancing LLM functionality through advanced machine learning techniques. Your work aims to continuously improve user experiences across our AI platform.

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Is experience with Large Language Models important for the Data Scientist role at Character.AI?

Absolutely! Experience with Large Language Models (LLMs) is crucial for the Data Scientist position at Character.AI, as supporting post-training optimization and leveraging these models for improved content discovery is a key responsibility of the role.

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Common Interview Questions for Data Scientist, Post Training
How do you approach the optimization of large language models?

When optimizing large language models, I focus on techniques such as fine-tuning based on specific datasets, assessing model performance using offline evaluation frameworks, and prioritizing user feedback to inform enhancements. It's critical to iterate quickly and make data-driven decisions.

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Can you explain your experience with search retrieval algorithms?

In my previous roles, I've developed and implemented search retrieval algorithms that prioritize relevance and accuracy. This includes fine-tuning heuristics and metrics to ensure users receive the most pertinent results while continually analyzing performance for further optimizations.

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What strategies do you use for A/B testing in machine learning models?

I adopt a systematic approach to A/B testing, including clearly defining success metrics, ensuring randomization to avoid bias, and carefully analyzing the results to validate hypotheses. Continuous monitoring and feedback are key to improving subsequent tests.

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Describe a time when you had to drive impact through data.

In a previous position, I identified inefficiencies in our recommendation system using user engagement metrics. By optimizing the algorithm and implementing new features based on my findings, we saw a significant increase in user interactions and satisfaction.

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What challenges have you faced while implementing ML frameworks, and how did you overcome them?

One challenge I faced was integrating new ML frameworks with legacy systems. I overcame this by advocating for a phased implementation plan, conducting rigorous testing, and providing documentation and support for my team to ease the transition.

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How do you ensure the relevance of recommendation systems?

To ensure relevance in recommendation systems, I continuously analyze user behavior patterns and segment users based on their interactions. Implementing machine learning algorithms that adapt to changing user preferences is essential for maintaining system effectiveness.

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What methods do you use to validate the performance of your models?

I use comprehensive evaluation frameworks that encompass offline metrics such as accuracy and recall, as well as online metrics like click-through rates and user engagement. Collecting qualitative feedback is equally important for a well-rounded performance assessment.

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How have you collaborated cross-functionally in prior roles?

In previous roles, I've collaborated closely with product, engineering, and UX teams to align our technical capabilities with user needs. Regular sync-up meetings, joint brainstorming sessions, and open lines of communication were key to successful project outcomes.

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How do you handle data discrepancies when measuring model performance?

I approach data discrepancies by first conducting a thorough investigation to identify potential sources of error or misinterpretation. Adjustments are made to data collection methods, and additional validations are implemented to ensure accurate measurement moving forward.

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Why do you want to work as a Data Scientist at Character.AI?

I'm excited about the opportunity to work at Character.AI because of its commitment to innovation in consumer AI and its meaningful impact on users. I'm eager to contribute my expertise in ML and search optimization to help further enhance user experiences across the platform.

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Character.ai is a neural language model chatbot service provider based in California that leverages sophisticated language models to facilitate conversations with users. Our mobile app had over 1.7 million downloads within its first week in 2023.

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Full-time, remote
DATE POSTED
December 13, 2024

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