# Comparing and sampling populations

2 videos
3 skills
When we are trying to make a judgement about a population, it is often impractical (or impossible) to observe every member of the population. Imagine trying to survey all 300+ million Americans to understand the likely outcome of the next presidential election! Because of this, much of statistics is collecting data from a representative and random sample. From the data collected from this random sample we can infer things about the greater population.

### Reasonable samples

VIDEO 4:17 minutes
To make a valid conclusion, you'll need a representaive, not skewed, sample.

### Valid claims

PRACTICE PROBLEMS
Practice figuring out whether we took a random sample and whether we're able to draw valid conclusions from our data.

### Making inferences from random samples

PRACTICE PROBLEMS
Given a random sample, practice figuring out what can we reasonably infer about the entire population?

### Comparing distributions with dot plots (example problem)

VIDEO 4:00 minutes
Sal examines two distributions in dot plots to draw conclusions about the times of Olympic swimmers.

### Comparing distributions

PRACTICE PROBLEMS
Practice comparing distributions that are presented in dot plots, histograms, and box plots.