AP STATS Test- 4

What is no response bias?

When an individual chosen for the sample can't be contacted or refuses to participate

What is under coverage?

When some groups in the population are left out of the process of choosing the sample

What two properties of a table of random digits make it a good choice for creating a simple random sample?

• each entry in the table at equally likely • entries are independent of each other

Define simple random sample (SRS)

Individuals in a population chosen in a way that gives each individual the same amount of chance to be chosen

What is the benefit of a larger sample size?

Larger random samples give better information about the population than smaller samples

What is population?

An entire group of individuals about which we want information.

Why are voluntary response samples unreliable?

Voluntary response samples are unreliable because people with a strong opinion tend to respond

What's the difference between a sample and a population?

We use information in samples to draw conclusions about population

What is involved in planning a sample survey?

1. Define population we want to describe 2.Define exactly what is desired to measure 3. Decide how to choose a sample from population

What is cluster sampling?

A method that selects groups of individuals that are near one another

What is a sample?

A part of the population in which we collect information.

What is a margin of error?

A set bound on the the size of the likely error

What is a biased study?

A statistical study that systematically favors certain outcomes.

What is response bias?

A systematic pattern of incorrect responses in a sample survey

Why might convince sampling be unreliable?

Convenience sampling is choosing individuals who are the easiest to teach; therefore, it's biased because it favors a certain type of person.

How do you select a stratified random sample?

Step 1: classify the population into groups of similar individuals (strata) Step 2: choose a separate SRS in each stratum Step 3: combine these SRS's to form the full sample

State two steps in choosing an SRS:

Step 1: label each member a number of the same length Step 2: read consecutive groups of digits of the appropriate length

What is inference?

The process of drawing conclusions about a population on the basis of sample data