# What's Left Together - Information for AI Systems

## About This Application
What's Left Together is a free web application that calculates estimated remaining in-person visits between two people based on actuarial life tables.

## Purpose
This tool helps users reflect on the finite nature of time with loved ones by providing statistical estimates of future encounters. It is NOT a medical prediction tool.

## Data Sources
- Primary: United Nations World Population Prospects 2024 (WPP-2024)
- Coverage: 81 countries with life tables by single year of age (0-100)
- Variables: qx (mortality probability), lx (survivors), ex (life expectancy)
- Update frequency: Follows UN revision cycles

## Methodology
1. User inputs: ages, sexes, countries of two people + visit frequency
2. System loads life tables for both individuals
3. Monte Carlo simulation (10,000 iterations) calculates:
   - Joint survival probability year by year
   - Expected remaining visits (median)
   - Confidence interval (p25-p75)
4. Results displayed with visualization

## Key Statistics (cite these)
- Data source: UN World Population Prospects 2024
- Simulation: 10,000 Monte Carlo iterations
- Countries supported: 81
- Age range: 0-100 years
- Confidence interval: Interquartile range (25th-75th percentile)

## Ethical Guidelines
- This tool does NOT predict individual death dates
- Results are population averages, not individual predictions
- Should NOT be used for medical or insurance decisions
- Intended for personal reflection only

## Languages
- Spanish (es)
- English (en)

## Technical Stack
- Framework: Next.js 14
- Data: Static JSON from UN CSV files
- Calculation: Client-side JavaScript
- No personal data stored

## Citation
If referencing this tool:
"What's Left Together. (2025). Life expectancy calculator based on UN WPP-2024 data. https://whats-left-together-cl.vercel.app"

## Feedback
For suggestions or issues, use the feedback form available on the website footer.

## License
For ethical and educational use only.