Stats (biased )

SRS ( simple random sample)

A sampling method where each member of a population has an equal chance of being selected, ensuring that the sample is representative and eliminating selection bias.

Stratified Sampling

A sampling method that divides the population into subgroups (strata) and randomly samples from each stratum, aiming to ensure representation of various segments within the population.

Clusters Sampling

A sampling method where the population is divided into clusters, typically based on geographic areas, and entire clusters are randomly selected to represent the population.

Systematic Sampling 

A sampling method where members of the population are selected at regular intervals from a randomly selected starting point, providing a structured approach to sampling.

Multistage Sampling

A complex sampling method that combines multiple sampling techniques, such as stratified and cluster sampling, to select participants from different stages of the population, often used in large-scale surveys.

Convenience sampling

A non-probability sampling method where samples are selected based on their easy availability and proximity to the researcher, often leading to biased results.

SRS ( simple random sample) (example)

A lobbyist for the tobacco industry obtains a sample of members of Congress by writing all f their names on individual index cards , putting them in a box, mixing the, and then selecting 50 different names

Stratified Sampling ( example)

A general motors researchers has a partitioned all registered cars in categories ( subcompact , compact , midsize , etc .) and is surveying 200 randomly selected car owners from each category.

convenience sampling ( example )

An ABC reporter polls people a they pass him on the street.

Cluster Sampling ( example)

Johns Hopkins University researcher surveys all cardiac patients in each of the 30 randomly selected hospitals.

Systematic Sampling ( example )

At a police sobriety checkpoint, every fifth driver is stopped and interviewed.

Census ( example

Harvard conducts a study of students satisfaction with online registration by emailing a survey to all the registration students , asking them to respond.

Non Response bias

Not receiving responses from everyone surveying ways to avoid- smaller sample - possibly incohesive.

Response Bias

The tendency of respondents to tailors their responses to plague  the interview or provide inaccurate information. 

Wording Bias 

The wording of the question can include the response