AP STATS PRAY FOR ME

Population

A group of individuals that belong to the same species and live in the same area

Sample

a subset of the population

sample survey

a study that asks questions of a sample drawn from some population in the hope of learning something about the entire population

simple random sample

every member of the population has a known and equal chance of selection

stratified random sampling

A form of probability sampling; a random sampling technique in which the researcher identifies particular demographic categories of interest and then randomly selects individuals within each category.

Systematic Random Sample

A sample where every kth individual is selected from a list or queue.

Cluster Sample

obtained by selecting all individuals within a randomly selected collection or group of individuals

multistage sampling

a probability sampling technique involving at least two stages: a random sample of clusters followed by a random sample of people within the selected clusters

observational study

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

experiment

A research method in which an investigator manipulates one or more factors to observe the effect on some behavior or mental process

explanatory variable

a variable that we think explains or causes changes in the response variable

confounding variable

a factor other than the independent variable that might produce an effect in an experiment

Lurking Variable

a variable that is not among the explanatory or response variables in a study but that may influence the response variable

Control

In an experiment, the standard that is used for comparison

Random Assignment

assigning participants to experimental and control conditions by chance, thus minimizing preexisting differences between those assigned to the different groups

Replication

repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding extends to other participants and circumstances

completely randomized design

the treatments are assigned to all the experimental units completely by chance

Experimental Units

the smallest collection of individuals to which treatments are applied

Factors

Numbers that are multiplied together to get a product

Treatment

a specific condition applied to the individuals in an experiment

double-blind procedure

an experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebo. Commonly used in drug-evaluation studies.

single-blind study

study in which the subjects do not know if they are in the experimental or the control group

Matched Pairs

A common form of blocking for comparing just two treatments. In some matched pairs designs, each subject receives both treatments in a random order. In others, the subjects are matched in pairs as closely as possible, and each subject in a pair is randomly assigned to receive one of the treatments.

block design

the random assignment of subjects to treatments is carried out separately within each block