AI GLOSSARY
Training Data
Training data is the foundation on which AI models learn. It determines the quality, fairness, and limitations of every model—more so than any algorithm. Those who have good training data can use AI successfully. Those who don’t will fail, regardless of the model.
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Data Types
Text, image, audio, video, tabular
Quality Factors
Quantity, Variety, Timeliness, Labels
Challenges
Bias, Data Protection, Costs, Rights
Best Practices
for a Strong Data Foundation
Why Training Data Determines AI Success
Machine learning is 80 percent data work and 20 percent modeling. If you skimp on the data, there’s no way to salvage the model. Training data is the most important investment in an AI project—the time, cost, and care are well worth it.
Quality is inherited
An AI model is only as good as its training data — “garbage in, garbage out.”
Ensuring Representativeness
If certain groups are missing from the data, the model will later fail to perform well for those groups.
Legal Basis
Training data is subject to copyright and data protection laws—this must be clarified.
Ethical Responsibility
Bias in data becomes bias in the model—be sure to avoid it.
Competitive Advantage
A company’s proprietary data is often the key advantage over standard models.
Compliance Framework
The AI Act requires proof of data quality and origin.
What is training data?
Training data is the dataset used to train an AI model. In supervised learning, it includes inputs and the correct answers (labels). In unsupervised learning, it includes only the inputs. For foundation models: massive collections of text, images, or multimedia.
Key quality factors: volume (more is often better, but marginal utility decreases), diversity (all relevant cases and groups are represented), timeliness (data must reflect the current state of the world), accuracy of labels (incorrect labels are worse than missing ones), balance (no overrepresented classes), legal clarity (usage rights, GDPR).
Sources: Company data (from ERP, CRM, ticketing systems—usually the gold standard), public datasets (Kaggle, Hugging Face—for baselines), web data (legally complex), Synthetic data (AI-generated—growing in importance), purchased data (specialized providers for niche areas).
For small and medium-sized businesses, training data is often the bottleneck. Important: systematically tap into your own data assets (feedback loops, historical data), take data quality seriously (labeling, cleaning), and pragmatically supplement missing data (public data, synthetic data, transfer learning).
Training Data Techniques in Detail
These eight techniques are helpful for training data projects:
Data Sourcing
Data Cleaning
Feature Engineering
Data Labeling
Data Augmentation
Synthetic data
Data Versioning
Data Governance
Best Practices for Training Data
These six principles have proven effective:
- Start small, expand iteratively: Begin with just a few good examples, then scale up.
- Check for representativeness: Are any groups or cases missing? Explicitly double-check.
- High label quality: Fewer but correct labels are better than many incorrect ones.
- Data versioning: Ensure each model version is traceable to the data state at that time.
- Actively manage bias: Identify and correct discriminatory patterns in the data.
- Build in a feedback loop: Production provides new training data — continuous improvement.
Source 1
Company Data
In-house history from ERP, CRM, and ticketing systems. Usually the gold standard.
Internal
Source 2
Public Data
Kaggle, Hugging Face, scientific datasets. For baselines and supplementary data.
External
Source 3
Synthetic Data
AI-generated. Growing importance—for bias, data privacy, and rare classes.
Synthetic
Common Errors in Training Data
We often see these pitfalls:
- Data leakage: Test data creeps into the training set—the model performs well but fails in production.
- Ignored Bias: Discriminatory patterns are carried over—the model automatically discriminates.
- Outdated data: Training data from three years ago — does not reflect the current world.
- Unclear Rights: Web data used without verification — copyright risk.
- Insufficient diversity: Only one region, language, or user group—the model fails elsewhere.
Training Data vs. Test Data vs. Validation Data
Three datasets with different roles:
- Training data: The model learns from this. Usually 70–80 percent of the dataset.
- Validation data: Used for hyperparameter tuning and interim evaluation. Usually 10–15 percent.
- Test data: Used only once at the end—for the final objective evaluation. Usually 10–15 percent.
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Frequently Asked Questions About Training Data
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How much training data do you need?
For traditional machine learning: 100–10,000 per class. Deep learning: 10,000+. For LLMs using few-shot learning: sometimes as few as 5–50 examples.
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What is data labeling?
People evaluate examples with the correct labels—category, bounding box, text transcription. This is usually the most expensive training step.
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What is synthetic data?
AI-generated training data — for bias reduction, data protection, or rare classes. Growing importance.
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What is a Golden Set?
A carefully curated, high-quality reference dataset — serving as a benchmark for model quality.
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How do you deal with bias in data?
Proactively search: Examine distributions, identify underrepresented groups. Then take steps to address the imbalance—sampling, synthetic data, reevaluation.
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How much does labeling cost?
Simple classification: 0.10–0.50 EUR per example. Complex annotation (image, video): 1–10 EUR. With 10,000 examples, the cost can quickly reach 10,000–50,000 EUR.
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How is training data related to data governance?
Data governance ensures that training data is legally sound, documented, and quality-assured—the foundation of AI compliance.
Systematically Build Training Data with prodot
In a free initial consultation, we’ll review your data landscape and outline a path to reliable training data for your AI projects.
As an AI partner for small and medium-sized businesses, we build training data pipelines in a pragmatic way—with a focus on quality, fairness, and compliance.
What We Offer
- AI Consulting — Data Strategy and Implementation.
- Data Governance — the foundation for management.
- Feature engineering —tailoring data to the model.
- Bias and Distortion — the core ethical issue.