Sample Size, Randomization and Bias
This topic becomes much easier when we connect the concept to a real business problem instead of memorizing definitions.
Chapter Overview
A good experiment starts before results are collected. If sample size is too small or user assignment is biased, the final result may be misleading.
Three Critical Ideas
Sample size affects reliability, randomization reduces selection bias, and experiment duration should cover natural variation such as weekday versus weekend behavior.
Common Mistake
Beginners often stop the test too early when they see a temporary increase. This can produce false confidence and poor business decisions.
Student Reminder
Design quality matters as much as statistical analysis. A weak experiment cannot be rescued later by fancy charts.
Key Takeaways
- Learn why experiment design matters before looking at results.
- This chapter belongs to A/B Testing & Experiment Analysis and is written in a simple student-friendly style.
- Practice with experiment examples to build confidence faster.
