Stat Unit 4 Vocab Words

population

the entire group of individuals you want to study

census

when data is collected from all individuals in a population

sample

a subset of the population; often use samples to make inferences about the population

bias 

a study flaw that leads to unrepresentative and/or inaccurate estimates 

voluntary response bias

this occurs when a sample is composed of volunteers who may differ from individuals who don’t choose to volunteer

confounding variable

provide alternative explanations for trends between explanatory and response variables

experimental units 

the individuals/subjects that are assigned to different treatments 

statistics

when we use samples to make inferences about populations

convenience sample

this occurs when individuals who are easy to reach are selected to be in sample

undercoverage bias

this occurs when part of the population has a reduced chance of being included in a sample

experiment 

a study in which a treatment is imposed on subjects 

explanatory variable

in an experiment, this is a variable that is purposely manipulated and may cause a change in the response variable

response variable

the measured experiment outcome that is compared between treatment groups 

observational study

observes individuals and measures variables of interest but does not attempt to influence the responses

simple random sample 

a sample of size n, chosen in such a way that every group of n individuals in the population has an equal change to be selected as the sample 

nonresponse bias

even if equally likely to be selected, not all are equally likely to provide a response

stratified random sample

a sample selected by choosing a simple random sample from each stratum of a population and combining them into one overall sample

systematic random sample 

selects a sample from an ordered arrangement of the population by randomly selecting one of the first k individuals and choosing every kth individual thereafter 

treatments

a specific condition applied to the individuals in an experiment

cluster sample

this type of sample consists of each member of randomly selected groups, sample all from some groups

placebo

an inactive treatment

good estimates

the purpose of this is to provide a baseline for comparison

placebo effect

when a fake treatment works

completely design randomized 

an experimental design in which experimental units are assigned to treatments completely at random