AP Stat - Sampling Methods and Biases

bias

a systematic error in measuring the estimate that would repeatedly cause the data to be wrong

voluntary response bias

people select themselves to participate in the study

nonresponse bias

individuals who are randomly chosen for the sample can't be contacted or refuse to cooperate

convenience

sampling

asking people who are easy to ask and not random.

undercoverage

bias

some groups are left out of the selection process

response bias

when respondents provide inaccurate or false answers to questions

wording bias

when wording of the question influences the answers

that are given

Simple Random Sample (SRS)

every individual has an equal chance of being chosen

Stratified

random

sample

population is divided into similar groups (strata) and then a SRS is used to select a FEW from ALL groups.

Cluster random sampling

population is divided into groups called clusters and then use a SRS to select ALL from a few groups.

Systematic Random Sampling

randomly select a number between one and n and survey every nth person after that

Voluntary response bias example

online polls, Instagram story polls

Nonresponse bias example

Mailed polls, phone call surveys

Convenience

sampling bias example

Asking your friends, nearby classmates

Undercoverage

bias example

Surveying only magnets students or CAP students

Response bias example

If a Cheerleader in their cheerleading outfit asks, "Is Cheerleading a sport?"

Wording bias

If Mr. Pham asks, "Isn't the Commanders the very best team in the NFL?"

Population

The entire group of individuals

Census

Survey the entire population

Sample

A subgroup of the population