Head First Statistics

Chapter 11. Estimating Populations and Samples: Making Predictions

Wouldn’t it be great if you could tell what a population was like, just by taking one sample?

Before you can claim full sample mastery, you need to know how to use your samples to best effect once you’ve collected them. This means using them to accurately predict what the population will be like and coming up with a way of saying how reliable your predictions are. In this chapter, we’ll show you how knowing your sample helps you get to know your population, and vice versa.

So how long does flavor really last for?

With your help, Mighty Gumball has pulled together an unbiased sample of super-long-lasting gumballs. They’ve tested each of the gumballs in the sample and collected lots of data about how long gumball flavor within the sample lasts.

There’s just one problem...

To satisfy the CEO, we’re going to need to find both the mean and the variance of flavor duration in the whole Mighty Gumball population.

Here’s the data we gathered from the sample. How do you think we can use it to tell us what the mean of the population is?

Note

Here’s how long flavor lasts for in minutes

61.9	62.6	63.3	64.8	65.1
66.4	67.1	67.2	68.7	69.9

Brain Power

Take a look at the data. How would you use this data to estimate the mean and variance of the population? ...