Designing Nemotron-Personas: Multi-Locale Synthetic Personas Powering Nemotron Training

Yev MeyerPrincipal Research Scientist at NVIDIA

Dane CorneilResearcher at NVIDIA

The Nemotron-Personas HF collection is a growing family of multilingual, region-specific synthetic persona datasets (currently covering seven countries and nine language variants with roughly 53 million personas in total), each grounded in real-world demographic and geographic distributions. Behind every dataset is the same NeMo Data Designer compound-AI pipeline, adapted per region. And while the public release is a useful artifact in its own right, what’s less visible is just how much these personas show up in Nemotron model training itself: seeding long-context samples, tool-use rollouts, formal-logic data, safety refusals, and general chat. This post pulls back the curtain on both halves of that story: how the collection is built, and how it is used.

Want to dive straight into code? Open the companion Colab notebook — or read on for the full story.

The growing Nemotron-Personas collection powering Nemotron model training. Multi-locale synthetic personas grounded in real demographic, geographic, and personality-trait distributions.

Why grounded synthetic personas matter

It’s easy to underestimate what a really good persona seed buys you. Three angles worth keeping in mind:

1. Distributional faithfulness for sovereign AI. Models trained on synthetic data that doesn’t reflect the actual demographics of a region inherit subtle biases: over-representing some groups, under-representing others, getting cultural context wrong. For sovereign-AI work, this matters a lot. Grounding personas in census + administrative data closes that gap before the LLM ever sees the data.

2. Diversity that random sampling can’t produce. “Generate 10,000 customer queries” with no seed and an LLM will give you 10,000 variations on the same handful of latent personas. Conditioning each query on a distinct, demographically-grounded persona forces the model to span the actual population it’ll be deployed against — the conscientious 62-year-old retired electrician in Pittsburgh, the 24-year-old graduate student in Bengaluru, the elementary-school teacher in Lille. Each yields a meaningfully different prompt.

3. Reusable seed material. Once a persona has a name, a demographic profile, an OCEAN vector, and a coherent backstory, any downstream pipeline can attach to it: a tool-use environment, a long-context construction, a safety-refusal template, a roleplay scenario. The collection acts as a library — generate the personas once, reuse them across training stages.

Nemotron-Personas inside Nemotron training

The Nemotron 3 Super Technical Report shows just how foundational these personas have become. They’re a seeding primitive used across many post-training stages.

Long-context samples

Long-context training data is hard to source. You need genuinely long, coherent sequences that aren’t just concatenations of unrelated documents. Persona records, by virtue of being self-contained narratives with rich attributes, concatenate cleanly:

“We also construct long-context samples by concatenating records from Nemotron-Personas-USA to reach the required sequence length.”

— Nemotron 3 Super Technical Report

Each persona is internally coherent (the OCEAN traits inform the cultural background, which informs the career goals, which informs the professional persona, etc.), and across personas the records are independent — exactly the right shape to pack into long sequences.

General-purpose tool-use rollouts

Tool-use trajectories require a user with a goal, not just a tool set. The Super pipeline uses a dual-LLM setup where one LLM plays the user and another plays the agent:

“The User-LLM is seeded with the selected tool set, a persona sampled from Nemotron-Personas-USA…”

— Nemotron 3 Super Technical Report

Seeding the user side with a real persona is what makes the rollouts feel like authentic conversations — the user’s goals, communication style, and frustration patterns all flow from their underlying attributes. The agent has to handle the variance that real users actually produce, not the narrow band of “well-behaved benchmark user” prompts.

A closely related approach was used to build Nemotron-Nano-9B-v2-Japanese, NVIDIA’s Japanese small language model that ranks #1 on the Nejumi LLM Leaderboard. The Japanese instruction-following + general-chat data was seeded by Nemotron-Personas-Japan, with prompts and assistant responses anchored to Japanese-grounded personas. A Japanese persona collection, generated by a localized DD pipeline, becomes the seeding layer for a Japanese model that beats the leaderboard.

The same template is being used across the family — instruction-following and general-chat data going into Nemotron Nano v3 and Super v3 follows the same persona-seeded recipe.

Synthetic formal-logic data

Even abstract reasoning data benefits from persona conditioning:

“We introduced variability into the generated scenarios, premises, and formulas by incorporating random personas, letters, and/or logic connective (i.e., ∧, ∨, ⊃, ≡, ∼) into the prompt.”

— Nemotron 3 Super Technical Report

Formal-logic problems become more diverse — and more transferable — when the surface scenario shifts. A propositional-logic puzzle about an elementary teacher planning a field trip exercises the same underlying inference as one about a credit-counselor evaluating a loan, but the lexical surface looks completely different. Persona-driven scenario variation breaks the model out of the canonical “Alice and Bob” rut that plagues most synthetic formal-logic datasets.

Sensitive-safety-category-refusals (SSCR)

The SSCR dataset — used in Nemotron’s safety blend — leverages Nemotron-Personas as seed data when constructing prompts that require refusal across sensitive categories. Personas matter here because real-world adversarial / sensitive prompts come from all kinds of users; grounding the synthetic prompts in demographically diverse personas ensures the trained refusal behavior generalizes across user populations rather than overfitting to a narrow band of “obviously suspicious” phrasings. SSCR is included in the broader nemotron-safety-blend.

General chat and instruction following

The same persona-seeding pattern that powers tool-use rollouts also powers the broader general-chat and instruction-following data that flows into Nemotron Nano v3 and Super v3. A chat or instruction sample is a function of who is asking — their goals, their constraints, their communication style — and personas are how the pipeline encodes “who.”

How they’re built: a four-stage compound-AI pipeline

Across all locales, the construction pipeline is the same four-stage shape (the regional adaptations live in the seed distributions, the language of the prompts, and which locale-specific fields get added). NeMo Data Designer orchestrates the pipeline as a column DAG:

The compound-AI pipeline behind Nemotron-Personas. Multiple models (PGM, OCEAN, LLM A, LLM B) work together to produce internally-coherent and diverse synthetic personas that mirror real-world demographic, geographic, and personality-trait distributions.

Stage 1: OCEAN Big-Five sampling

OCEAN (Big Five personality traits) is the most empirically grounded model of human personality. For each persona we sample five trait T-scores (μ = 50, σ = 10, clipped to [20, 80]), bucket each into a coarse label, and attach a prose description grounded in the personality literature. Working at the description level (rather than raw scores) is what makes the downstream LLM stages produce nuanced, internally-consistent narratives — “highly conscientious” vs “highly extraverted” reads very differently to an LLM than t_score=72.

The score-to-label mapping is shared across all five traits:

Each (trait, label) pair maps to a curated description that captures how that level of the trait actually manifests. A representative slice of the openness mapping:

The other four traits each have their own 5-row description table tuned to their domain (conscientiousness around organization vs spontaneity, extraversion around social energy, agreeableness around cooperation, neuroticism around emotional reactivity). The result is that one sampled persona arrives at Stage 3 with a structured personality block:

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{
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  "openness":          {"t_score": 67, "label": "high",      "description": "Curious and appreciative of art..."},
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  "conscientiousness": {"t_score": 72, "label": "very high", "description": "Exceptionally organized..."},
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  "extraversion":      {"t_score": 41, "label": "low",       "description": "Generally reserved..."},
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  "agreeableness":     {"t_score": 55, "label": "average",   "description": "Generally cooperative..."},
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  "neuroticism":       {"t_score": 38, "label": "low",       "description": "Emotionally stable..."},
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}

…which the downstream LLM prompts reference directly via Jinja templates:

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Personality profile:
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- {{ openness.description }}
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- {{ conscientiousness.description }}
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- {{ extraversion.description }}
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- {{ agreeableness.description }}
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- {{ neuroticism.description }}

Stage 2: Demographically-grounded sampling

This is the engine of regional fidelity. For each locale, the goal is to produce a demographic record whose attributes correlate with each other the way real populations do — age × education × occupation × marital status × geography, with locale-specific extensions. Naive independent sampling produces nonsensical records (3-year-old surgeon married for 30 years living alone in Singapore); the released artifact pulls from Probabilistic Graphical Models trained on real statistical distributions (census tables, administrative records, public surveys) so the correlations are statistically faithful.

The simplest path to seed your own pipeline today is to consume the released NGC-hosted Nemotron-Personas dataset directly via Data Designer’s built-in PersonSampler. This gives you the full demographic + OCEAN block from a verified PGM-grounded source without rebuilding anything yourself. One SamplerColumnConfig is enough:

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import data_designer.config as dd
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config_builder.add_column(
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    dd.SamplerColumnConfig(
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        name="person",
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        sampler_type=dd.SamplerType.PERSON,
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        params=dd.PersonSamplerParams(
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            locale="en_US",                  # or ja_JP, en_IN, fr_FR, ko_KR, pt_BR, en_SG, hi_Deva_IN, hi_Latn_IN
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            age_range=[18, 114],
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            with_synthetic_personas=True,    # exposes Big Five + persona attributes
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        ),
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        drop=True,
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    )
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)

{{ person.openness.description }}, {{ person.occupation }}, {{ person.district }} all become available to downstream Jinja templates immediately. See the Person Sampling docs for the full setup walkthrough (NGC API key + data-designer download personas --locale en_US).

Stage 3: Persona attributes via structured outputs

With OCEAN traits and demographic grounding in hand, the pipeline calls a reasoning LLM with a single LLMStructuredColumnConfig that materializes six rich attribute fields in one shot via a Pydantic schema:

Stage 3: a single LLMStructuredColumnConfig call materializes six persona-attribute fields (cultural background, skills, career goals, hobbies, plus list variants) from the PGM + OCEAN seed.

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from pydantic import BaseModel, Field
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class PersonaAttributes(BaseModel):
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    cultural_background: str = Field(description="Description of the person's cultural background")
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    skills_and_expertise: str = Field(description="Description of the person's skills and expertise")
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    skills_and_expertise_list: list[str] = Field(description="List of the person's skills and expertise")
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    career_goals_and_ambitions: str = Field(description="Description of the person's career goals and ambitions")
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    hobbies_and_interests: str = Field(description="Description of the person's hobbies and interests")
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    hobbies_and_interests_list: list[str] = Field(description="List of the person's hobbies and interests")
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config_builder.add_column(
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    dd.LLMStructuredColumnConfig(
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        name="persona_attributes",
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        system_prompt=PERSONA_ATTRIBUTES_SYSTEM_PROMPT,
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        prompt="""\
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Based on a person with the following profile:
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Name: {{ first_name }} {{ middle_name if middle_name else '' }} {{ last_name }}
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Sex: {{ sex }}
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Age: {{ age }}
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...
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Occupation: {{ occupation }}
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Location: {{ city }}, {{ state }}, {{ county }}
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Personality profile:
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- {{ openness.description }}
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- ...
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- {{ neuroticism.description }}
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Generate the following detailed persona attributes:
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- cultural_background
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- ...
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- hobbies_and_interests_list
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When generating attributes, make sure to incorporate the influences suggested by the personality profile description.
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""",
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        output_format=PersonaAttributes,
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        model_alias=MODEL_ALIAS,
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        drop=True,
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    )
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)

The system prompt forces internal consistency (“attributes that are internally consistent and logically connected to the base persona details”), cultural sensitivity (“avoid stereotypes while acknowledging cultural influences”), and specificity (“create specific, detailed responses rather than generic ones”). Pydantic schema enforcement means every record’s attributes parse cleanly downstream.

Stage 4: Persona descriptions

The final stage is a second structured-output LLM call that synthesizes everything above into nine cohesive persona descriptions: professional_persona, finance_persona, healthcare_persona, sports_persona, arts_persona, travel_persona, culinary_persona, concise_persona, and a paragraph-length detailed_persona.

Stage 4: a second structured-output LLM call synthesizes nine cohesive persona descriptions spanning professional, finance, healthcare, lifestyle, and creative dimensions.

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class Personas(BaseModel):
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    professional_persona: str = Field(description="A one-sentence persona description including primary field of work, key professional skills...")
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    finance_persona: str = Field(description="A one-sentence persona characterization of spending habits, relationship with money, saving and investment habits...")
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    healthcare_persona: str = Field(description="A one-sentence persona description of very specific health conditions ... and their typical behavior as a patient...")
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    sports_persona: str = Field(description="A one-sentence persona description of athletic interests, seasonal sports, and their approach to fitness and exercise...")
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    arts_persona: str = Field(description="A one-sentence persona characterization of engagement with creative expression, artistic appreciation, cultural activities...")
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    travel_persona: str = Field(description="A one-sentence persona capturing travel interests and style, including planning preferences...")
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    culinary_persona: str = Field(description="A one-sentence persona description of food/cuisine preferences, cooking skill level...")
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    concise_persona: str = Field(description="A one-sentence description capturing the essence of this person's unique perspective and approach to life...")
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    detailed_persona: str = Field(description="A paragraph describing persona's cultural background, skills, goals, and interests...")
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config_builder.add_column(
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    dd.LLMStructuredColumnConfig(
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        name="personas",
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        system_prompt=PERSONA_SYSTEM_PROMPT,
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        prompt="""\
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Based on a person with the following persona attributes and profile:
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Age: {{ age }}
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Cultural background: {{ cultural_background }}
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{{ 'Hobbies and interests: ' + hobbies_and_interests if age >= 6 else '' }}
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{{ 'Skills and expertise: ' + skills_and_expertise if age >= 16 else '' }}
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{{ 'Career goals and ambitions: ' + career_goals_and_ambitions if age >= 16 else '' }}
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Personality profile:
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- {{ openness.description }}
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- ...
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- {{ neuroticism.description }}
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Generate the following self-contained persona descriptions that capture how persona attributes and profile combine to create a unique individual's perspective and approach to various facets of life.
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- professional_persona
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- ...
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- detailed_persona
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""",
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        output_format=Personas,
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        model_alias=MODEL_ALIAS,
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        drop=True,
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    )
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)

The system prompt contains explicit guardrails: include the name in every description, never directly mention cultural heritage (infuse it implicitly through practices and traditions), and always take age into account. The LLM does the synthesis; Pydantic does the validation; Data Designer’s DAG executes the whole thing in parallel across millions of records.

Building your own: the customization story

The released artifact is the general-purpose collection. In practice, most downstream pipelines that use these personas extend them in some way. NeMo Data Designer makes that trivial: the same LLMStructuredColumnConfig + ExpressionColumnConfig pattern that builds the released schema can be used to layer on any custom dimension you need.

The accompanying companion Colab notebook walks through a concrete example. After reproducing the released schema with a PersonSampler against the NGC-hosted dataset, the notebook adds a custom tech_persona dimension with two new fields: a prose description of the persona’s relationship with technology, plus a list of specific tech tools they use:

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import data_designer.config as dd
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from pydantic import BaseModel, Field
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class TechPersona(BaseModel):
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    tech_persona: str = Field(
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        description=(
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            "A 2-3 sentence description of this person's relationship with technology: "
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            "comfort with AI/digital tools, level of tech adoption, preferred devices, "
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            "and one specific way technology shapes their daily routine."
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        )
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    )
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    tech_tools: list[str] = Field(
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        description=(
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            "List of 4-6 specific tech tools, apps, services, or devices this person uses regularly. "
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            "Each entry should be a concrete named product, not a generic category."
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        )
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    )
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config_builder.add_column(
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    dd.LLMStructuredColumnConfig(
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        name="custom_persona",
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        system_prompt=(
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            "You write nuanced, specific tech-relationship personas grounded in demographic "
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            "and psychometric attributes. Avoid generic platitudes; ground every claim in the "
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            "person's age, occupation, personality, and lifestyle."
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        ),
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        prompt="""\
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Based on a person with the following persona profile:
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Name: {{ first_name }} {{ last_name }}, Age: {{ age }}, Occupation: {{ occupation }}
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Cultural background: {{ cultural_background }}
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Career goals: {{ career_goals_and_ambitions }}
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Hobbies: {{ hobbies_and_interests }}
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Personality profile:
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- {{ openness.description }}
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- {{ conscientiousness.description }}
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- {{ extraversion.description }}
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- {{ agreeableness.description }}
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- {{ neuroticism.description }}
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Generate the `tech_persona` and `tech_tools` fields per the schema.
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""",
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        output_format=TechPersona,
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        model_alias=MODEL_ALIAS,
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        drop=True,
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    )
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)
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config_builder.add_column(dd.ExpressionColumnConfig(name="tech_persona", expr="{{ custom_persona.tech_persona }}"))
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config_builder.add_column(dd.ExpressionColumnConfig(name="tech_tools", expr="{{ custom_persona.tech_tools }}"))

A representative output from the Colab run:

tech_persona  Megan pragmatically adopts mainstream tech, seamlessly weaving AI assistants
              into her lesson planning while preferring her well-worn iPad over flashier
              gadgets; technology shapes her workflow most when she's grading assignments
              on Sunday evenings.
tech_tools    ['MacBook Air', 'iPad Pro 12.9', 'iPhone 14', 'Google Classroom',
               'Microsoft OneNote', 'ChatGPT']

A few lines of Pydantic + one LLM column + a couple of expression columns and the released schema picks up two brand-new domain-specific fields. The same pattern scales: a healthcare provider extends with medical_history_persona and insurance_persona; a media company extends with media_consumption_persona and subscription_stack; a financial-services team extends with investment_persona and risk_tolerance_persona. The PGM-grounded base record stays the seed; everything else is one schema away.

Going deeper: build a brand-new locale

For locales without an NGC-hosted Nemotron-Personas dataset, the build path is open. The OCEAN Big-Five helpers ship in the companion Colab notebook (Stage 1 of the original pipeline), and NeMo SDG-PGMs provides the framework for building your own demographic PGM (Stage 2) — collect aggregate statistical distributions, declare a PGMGenerator subclass (the us_person example is a working blueprint), and plug it into Data Designer via SDG-PGMs’s PGMGeneratorPluginConfig column generator. The downstream LLM stages (3 and 4) are locale-agnostic; they just need the right language in the prompts. The notebook leaves a SAMPLE_FROM_SDG_PGM = True toggle in place as the integration point.

Try it yourself

The companion Colab notebook covers every detail in this post end-to-end, from the NGC dataset bootstrap through the toy custom-persona example.

Switching locales is a one-liner: change personas_locale = "en_US" to any of en_IN, en_SG, fr_FR, hi_Deva_IN, hi_Latn_IN, ja_JP, ko_KR, pt_BR (and run data-designer download personas --locale <code> once for the new locale). Everything downstream stays the same.

Closing thoughts

The headline number on the Nemotron-Personas HF collection is the persona count, but the real story is that a single, modular, locale-adaptable pipeline produces seed material that recurs throughout Nemotron’s training stack. Long-context construction, tool-use rollouts, formal-logic variability, safety refusals, instruction-following data — all of them lean on the same underlying primitive. Building the right primitive once means many downstream pipelines stop being one-off projects.

If you’re building region-specific synthetic data for your own model, the path is clear: take a locale’s released artifact, layer your domain-specific dimensions on top with a few lines of Data Designer config, and you have a custom dataset that inherits all the demographic grounding the original artifact carries.

Key Resources:

• Nemotron-Personas HF collection: huggingface.co/collections/nvidia/nemotron-personas
• NeMo Data Designer: github.com/NVIDIA-NeMo/DataDesigner
• NeMo SDG-PGMs: github.com/NVIDIA-NeMo/SDG-PGMs
• Nemotron 3 Super Technical Report: research.nvidia.com/labs/nemotron/…/NVIDIA-Nemotron-3-Super-Technical-Report.pdf
• Person Sampling in Data Designer: Person Sampling concept docs
• Related dev notes: Designing Data Designer: Why SDG Is a Systems Problem, Engineering an Enterprise-Grade Text-to-SQL Dataset, Push Datasets to Hugging Face Hub

Want to learn more about NeMo Data Designer? Check out our documentation and start building your own region-specific synthetic persona datasets today.