# Comparing and sampling populations

4 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.

### Inferring population mean from sample mean

VIDEO
10:03 minutes

Much of statistics is based upon using data from a random sample that is representative of the population at large. From that sample mean, we can infer things about the greater population mean. We'll explain.

### Reasonable samples

VIDEO
4:17 minutes

To make a valid conclusion you'll need a representaive, not skewed, sample

### Valid claims

PRACTICE PROBLEMS

### Mean absolute deviation word problem

VIDEO
5:46 minutes

Here's a word problem where we show you how to calculate the mean absolute deviation in order to compare two distances.

### Dot plot and distribution word problem

VIDEO
4:00 minutes

Let's examine the distribution of a dot plot to draw conclusions about the times of Olympic swimmers.

### Comparing populations

PRACTICE PROBLEMS

### Variation in samples

PRACTICE PROBLEMS