4.2 vocab ap stats

observational study

A study where the researcher observes and records behavior or outcomes without manipulating any variables.

response variable

The outcome variable that researchers measure to see how it is affected by changes in the explanatory variable.

explanatory variable

The variable that is manipulated or categorized to examine its effect on the response variable.

confounding

A situation in which the effects of two variables are mixed, making it difficult to determine their individual effects.

experiment

A research study in which the researcher manipulates one or more variables and observes the effect.

placebo

A substance with no therapeutic effect used as a control in testing new drugs.

treatment

The specific condition applied to the individuals in an experiment.

experimental unit

The smallest division of experimental material such that any two units may receive different treatments.

subject

An individual or item that is being studied or observed in an experiment.

factor

A variable that is systematically manipulated in an experiment to determine its effect on the response variable.

levels

The different conditions or values that a factor can take in an experiment.

control group

The group that does not receive the treatment in an experiment and is used as a baseline to compare results.

placebo effect

The phenomenon where participants experience real changes in their condition simply because they believe they are receiving treatment, even when they aren't.

double-blind

A study design in which neither the participants nor the researchers know who is receiving the treatment and who is receiving a placebo.

single-blind

A study design in which only the participants are unaware of whether they are receiving the treatment or a placebo.

random assignment

The process of randomly allocating subjects to different treatment groups to ensure that each group is similar and free from bias.

control

The process of keeping other variables constant in an experiment to isolate the effects of the treatment.

replication

The repetition of an experiment to confirm findings and ensure reliability.

completely randomized design

An experimental design in which all subjects are randomly assigned to treatments, ensuring that each subject has an equal chance of being assigned to any group.

block

A group of experimental units that are known to be similar to one another, which allows researchers to control for the variability among these units.

randomized block design

An experimental design that involves dividing subjects into blocks based on a certain characteristic and then randomly assigning treatments within each block.

matched pairs design

An experimental design in which subjects are paired based on similar characteristics, and each pair is then assigned to different treatments.