🪖 Recruiting participants §

• 😴 Convenience Samples
• 👥 Crowdsourcing Samples
• 🎰 Random Sampling and 🎰 Stratified Random Sampling
• ⏺️ Multi-Stage cluster sampling
• ❄️ Snowball sampling

💯 How many participants? §

few: cheap, lower relieability ↔ many: expensive, higher relieability → find a balance to get the maximum “bang for your buck”

🤙 Rules of thumb: §

• min. 30, aim for 50
• 10-20 data points per condition
• 🤙 Usability Testing: “85% of usability problems → 5 users”
• quantitative studies:
  • min 20 for statistical significance
  • 30 for 🚫 Central Limit Theorem
• card sorting:
  • min 15 per group
• exe-tracking:
  • min 39 for solid heatmaps