Stats– sampling

What is a population?

• A collection of individual people or items

• A finite sample of what you want to investigate

• An infinite sample of what you want to investigate

• A group of whatever you want to investigate

Name one disadvantage of censuses.

What is a sample?

• A collection of individuals or objects

• A sub-set of the population

• A group of people or objects

• A randomly selected individuals

What is one concern or caution with sampling?

What's one disadvantage when sampling?

A call center has 400 people operating the telephones. The manager decides that he needs to know how long the operatives are sepnding on each call. He times a random sample of 20 operators over one day and works out the mean time per call.

Suggest a sampling frame.

A call center has 400 people operating the telephones. The manager decides that he needs to know how long the operatives are sepnding on each call. He times a random sample of 20 operators over one day and works out the mean time per call.

What are the sampling units?

A call center has 400 people operating the telephones. The manager decides that he needs to know how long the operatives are sepnding on each call. He times a random sample of 20 operators over one day and works out the mean time per call.

Is the mean time the manager calculates reliable?

• Yes

• No

A call center has 400 people operating the telephones. The manager decides that he needs to know how long the operatives are sepnding on each call. He times a random sample of 20 operators over one day and works out the mean time per call.

Suggest which distribution we should use to model how long the operatives spend on each call.