Sampling
Compare weighted populations and sampling methods. Separate a method’s bias from variation in individual samples.
Population weights and averages
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Example
Example
What is the exact mean of the whole population?
A population has 11 members of Group A, each with value 5, and 8 members of Group B, each with value 15.
| Data values | Frequency | |
|---|---|---|
| Group A | 5 | 11 |
| Group B | 15 | 8 |
Choose an answer to try the example.
Why?
The sum of all values is 11 × 5 + 8 × 15. Divide by the population size 19.
(11 × 5 + 8 × 15)/19 = 175/19
Explore the idea
| Data values | Frequency | |
|---|---|---|
| Group A | 5 | 11 |
| Group B | 15 | 8 |
Sampling is with replacement: each draw returns to the population. Random samples vary; the population mean stays fixed.
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Question the sampleCompare weighted populations and sampling methods. Separate a method’s bias from variation in individual samples.
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Optional and off by default. Share starts, completions, replays and error categories. For visits from ChatGPT, starts and completions can also include the first QuickenBrain page and broad country. No answers, drawings or names.
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