# Lec28 Sampling Distributions and Standard Errors

### Understanding how sampling variability affects estimates.

### Announcements

- Problem Set 10 due at 5pm
~~today~~Tuesday 11/29 - Office hours
- Today 1pm-4pm
- Tuesday 9am-12pm

### Thought Experiment

Sample 3 students at random and get their (sample) mean age.

**Results**: Based on `set.seed(41)`

, Luisangelâ€™s favorite number.

**Question**: Why do the sample means below vary?**Answer**: Because of the*sampling variability*induced by the*random*sampling!

Random Sample | (Sample) Mean Age |
---|---|

Jack, Jared, Sam | 21.7 |

Wengel, Rebecca, Steven | 19.4 |

Stefan, Joccelyn, Sierra | 20.0 |

### In-Class

- Lec27-B learning check discussion
- Handout based on second figure of LC above
- Chalk talk on
- Sampling distributions
- Standard errors