Algebra 2 Honors vocab 11.1-11.2

statistical question

can be answered by collecting many pieces of information, or data, and summarizing the data.

ex: “What month has the most birthdays of students at your school?”

statistical variable

a quantity or quality that can be measured or counted, and for which data are expected to differ from one observation to another.

Two main types are categorical and quantitative.

categorical variable

Data that fall into categories, or that indicate a qualitative rather than quantitative attribute

ex: “What is your favorite Summer Olympic sport?”

quantitative variable

Numerical, that in the context of the data can be compared, added, subtracted or otherwise operated on, represent a second type of statistical variable

Ex: “What is the typical number of apps a teenager has on a smartphone?”

population

the set of all members of a group that you want to know something about

Ex: all high school graduates

sample

a subset of the population that is being studied to answer a statistical question about the population

Ex: 100 students were chosen out of a school of 1,000

parameter

a measure that describes a population

Ex: average weight of children aged 5-10

statistic

a measure that describes a sample of the population

Ex: the average income of a random sample of households.

Sample survey

asks every member of a sample the same set of questions and records the answers

Ex: A newspaper polls randomly selected residents in a town about which mayoral candidate they prefer

experiment

involves applying a treatment to some group or groups and measuring the effects of the treatments

Ex: A doctor conducts a clinical trial of a new blood pressure medicine by prescribing it to half the patients in the study and measurig the effect it has on their blood pressure

observational study

you measure or observe members of a sample in such a way that they are not affected by the study

Ex: A grocery store wonders how many customers bring reusable grocery bags to the store. They have an employee stand at the checkout and count the number of people using reusable bags.

bias

it systematically produces results that misrepresent a population

simple random sample

each member of the population is equally likely to be chosen, and each possible sample of the size you want is equally likely to be chosen

Stratified sampling

Population divided into groups based on similar characteristics; sample randomly chosen from each

Cluster sampling

Population divided into clusters; entire clusters chosen at random as the sample

Systematic sampling

First individual chosen at random; then use rule like “every 3rd person” to select sample

Convenience sampling

Only individuals that are in close proximity or easily accessible chosen for sample

risk of bias

Self-selected sampling

Sample composed entirely of volunteers

experimental group

a group of subjects who are exposed to the variable under study

Ex: Mice are assigned randomly to either group, and all mice are infected with the flu. This group receives the new drug.

Control group

a group of subjects who are not exposed to the variable under study

Ex: Mice are assigned randomly to either group, and all mice are infected with the flu. This group does not receive the drug.