# Summary of key words

Population
=
All

Census
=
A survey of the whole population

Sampling
=
Representation

Bias
=
A systematic error in a survey that can influence and skew the outcome of the data towards a certain direction

Random sampling
=
Equal chance examples include simple random sampling and stratified sampling

Stratified sampling
=
Sample every category

Cluster sampling
=
Everything in a couple of categories (also known as one-stage)

Multi-stage sampling
=
Sampled samples (also known as two-stage)

=
A question that guides the respondent to answer in a particular way

Opportunity sampling
=
Immediately available

Voluntary sampling
=
Volunteers give their views

Systematic sampling
=
Select every Kth subject