AP Stats 1.B Test

Explanatory variable

predicts, explains, or influences the response variable (outcome)

response variable

the measured outcome

confounding variable

variable associated with both explanatory and response variables and creates a doubt about a true causal connection between the explanatory and response variables

observational study

a study in which variables are observed without imposing any conditions or treatments

prospective observational study

analyzing data that are happening now and in the future

retrospective observational study

analyzing data that were already collected in the past

survey observational study

analyzing data gathered from responses to questions

direct observational study

analyzing data measured through observation or records or observations

experiment

study in which conditions, or treatments, are imposed on experimental units

experimental units

subjects, participants, or units to which treatments are assigned

treatments

different categories or levels of an explanatory variable that is imposed on experimental units

simple random sample (SRS)

sampling method in which every possible group of individuals in the population has an equal chance of section

generalizability

when individuals are reandomly selected from target populations, results can be generalized to the whole population

Judgement Sample (Nonrandom Sample)

use human judgement to select a sample

cluster random sample

divide population into groups. randomly select several groups, then sample every individual within the selected groups

stratified random sample

divide population into groups. within every group, randomly sample several individuals

systematic random sample

randomly select the first individual, then sample other individual at fixed intervals

bias

flaw in the sampling or measuring procedure that leads to systematically over or under understanding a parameter value

sampling bias

bias that comes from selecting a sample that is not representative of the population of interest

undercoverage bias

when part of the population is excluded or is less likely to be selected for a sample

nonresponse bias

when individuals who do not respond to surveys substantially differ from responders

voluntary response bias

when a sample consists of entirely volunteers, who differ from the general population

response bias

when responses to a survey differ from the true value

question wording bias

when survey questions are confusing or leading

self-reporting bias

when individual inaccurately report their own traits