Khan Academy: Determining Sample Size Based on Confidence and Margin of Error

Just how confident can we be with statistics calculated from a sample? Learners take this into account as they look at data from a sample of petroleum engineer salaries. They analyze the effect sample size has on a margin of error and...

Don't leave your classes vulnerable in their calculations! Help them understand the importance of calculating a margin of error to represent the variability in their sample mean. 

Increase your sample and increase your accuracy! Scholars complete an activity that compares sample size to variability in results. Learners realize that the greater the sample size, the smaller the range in the distribution of sample...

Where do all of these equations come from? A statistics video explains how to find the sample size equation based on the formula for the confidence interval. 

There are too many equations to memorize, but a helpful trick will make it easier. When you start with the confidence interval equation, the video walks through how to solve it and create the sample size equation.

Constructing small sample size confidence intervals using t-distributions.

Video discusses the effect of sample size on the sampling distribution. Shows using a simulation how as sample size increases the sampling distribution becomes more normal and the standard deviation decreases. Also discusses the effect...

Video reviews the central limit theorem and uses a simulation to illustrate sampling distributions and how they approach a normal distribution with larger sample sizes even if the original distribution was not normal. Also discusses the...

Video example of using a sample distribution to solve a problem determining the probability that a sample mean is below a certain number. Includes example of finding a z-score and looking it up in a table to determine the probability....

A video that demonstrates how to solve equations with variables on both sides. The first two examples give the equation and the third example is a word problem in which an equation must be written and then solved. This video is also...