Experimental Design Vocabulary

Vocabulary-style flashcards covering key experimental design terms and their definitions from Page 1 and Page 2.

Bias

any systematic failure of a sampling method to represent its population

Blinding

any individual associated with an experiment who is not aware of how subjects have been assigned

Blocking

Grouping experimental units by some factor that we are not testing if we believe that factor could affect the outcomes

Census

a sample that consists of the entire population

Cluster Sample

a sampling design that groups the population in a convenient way and then randomly selects groups to sample and collects data about the entire group

Confounding

a variable that has an effect on the experiment in a way that cannot be separated from the actual treatments; it is a reason we block

Control

a principle of experimental design; controlling any factor we can when designing an experiment

Control Group

the experimental units assigned to a placebo or standard treatment; it allows for comparison

Convenience Sample

sample taken of individuals that are easily selected

Double Blind Experiment

an experiment in which neither those who could influence the results nor those who evaluate the results know who was assigned to which treatment

Experiment

a process that imposes treatments on randomly selected or assigned subjects then compares the responses across treatment levels

Experimental Units

individuals on whom an experiment is performed; called subjects when people

Factor

a variable whose levels are controlled by the experimenter

Heterogeneous

different

Homogeneous

alike

Level

the specific value that an experimenter chooses for a factor

Matched Pairs

type of design that pairs subjects that are very similar in order to compare them to each other

Multistage Sample

sampling method that combines several sampling methods

Nonresponse Bias

bias introduced to a sample when a large portion of those sampled do not respond

Observational Study

a study that gathers data from a sample without imposing a treatment

Placebo

a treatment that has no effect

Placebo Effect

the tendency of experimental units to respond to treatment regardless of the type of treatment (even for the control group)

Population

the entire group of individuals or instances about whom we hope to learn

Prospective Study

a study in which individuals are selected and monitored for future behavior

Randomization

a principle of experimental design: the process of selecting subjects randomly

Replication

a principle of experimental design which requires many experimental units in each treatment

Response

a variable whose values are compared across different treatments

Response Bias

type of bias resulting from false information being given

Retrospective Study

a study in which individuals are selected and surveyed about past behavior

Sample

a representative subset of a population

Sampling Frame

complete list of individuals/items from which the sample is drawn

Simple Random Sample

a sample in which each item has an equal chance of being selected and every combination has an equal chance of being selected

Simulation

a sequence of random outcomes that model a situation

Statistically Significant

an observed difference that is too large to likely have occurred naturally

Stratified Random Sample

a sampling design that divides the population into homogeneous groups and random samples are selected from each group

Single Blind Experiment

an experiment in which either those who could influence the results or those who evaluate the results know who was assigned to which treatment, but not both

Systematic Sample

a sampling design that randomly selects the first item and then uses a pattern to select each additional item

Sampling Variability

the natural tendency of randomly drawn samples to differ, one from another

Treatment

the process or controlled circumstance applied to randomly assigned experimental units

Trial

the sequence of outcomes representing events that we are simulating

Under-coverage

a form of bias that samples in a way that part of the population gets less representation than it has in the population

Voluntary Response Bias

bias introduced to a sample because the individuals choose on their own to participate or not

Wording Bias

bias introduced by language of the question: language that favors one response over another, technical language used, etc.