AP Statistics TPS5e Chapter 4

dotplot

a display of quantitative data in which each data value is shown as a dot above its location on a number line

bias

systematic error, favoring some parts of the population over others; systematically favors certain outcomes

sample mean

x̄, the average of a sample

sample

a subset of an entire population used to gather information about the population

statistic

a number describing a sample

population

entire group of individuals that we want information about

parameter

a number describing a population

sampling frame

list of individuals from which a sample is actually selected

census

a sample that collects information from every individual in the population

probability sample

a sample chosen by chance

simple random sample (SRS)

a sample which consists of n individuals from the population chosen in such a way that every set of n individuals has an equal chance to be the sample actually selected; this gives every such sample and individual an equal chance to be chosen to avoid bias

stratified random sample

a sample constructed by dividing the population into groups (called strata) based on some characteristic, taking a SRS from each, and then combining these to form full sample [within each strata, individuals will be similar but when comparing one strata to another, the strata will vary from one another]

strata

groups formed of similar individuals; choosing a separate SRS from each of these groups and combining these SRSs creates a stratified random sample

cluster sample

take a SRS of several entire groups (clusters) of individuals that are "near" on another [within each cluster, individuals will be varied but when comparing one cluster to another, the clusters will be similar to one another]

systematic random sample

taking a sample by beginning at a randomly chosen location in a list and then every nth item thereafter

convenience sample

chooses individuals easiest to reach; one type of bad sample design; does not represent the entire population; biased because the person creating the sample is not selecting randomly

voluntary response sample

created by allowing people to choose themselves by responding to a general appeal; biased because people with extreme opinions are most likely to respond

explanatory variable or factor

a variable that may help explain or predict changes in a response variable (the variable that we change or manipulate in an experiment)

response variable or outcome

a variable that measures an outcome of a study

nonresponse

individual chosen for the sample can't be reached or does not cooperate