sampling plans

Simple random sampling

takes a random sample out of the population

Stratified random sampling

Divide population into common groups ie(north,east,west green)then take a random sample from each

Cluster sample

Separate the population into groups then every person from it as the sample

Systematic sampling

Choosing every 7th person

Random digit dialing

area code , a random cluster and then computer generates the last two numbers

Multistage sampling

Combines two sampling plans

Volunteer sample

Tv stations or magazines asking you to respond if you have an opinion

Convenient sample

Asking easiest accessible group

Validity

Accuracy measure

reliability

Consistency measure

Bias

Measurement that is consistently off the mark

margin of error

$$\frac{1}{\sqrt{n}}$$