AP Stats Ch. 2 DEAD Words

Definitions: https://www.mathwords.com/

Convenience Sample

A non-probability sampling method where you select individuals who are the easiest to reach or most readily available (not at random). Likely to be biased and cannot be generalized to the whole population.

Voluntary Response

A sample in which participants choose whether to respond, rather than being selected by the researcher. Results are almost always biased.

Simple Random Sample (SRS)

A sample chosen so that every possible group of n individuals from the population has the same chance of being selected. Eliminates selection bias by design.

Sampling WITHOUT Replacement

Where items (from data set) are chosen randomly, and once an observation is chosen it cannot be chosen again.

Stratified Random Sample

Method of collecting data by dividing the population into non-overlapping subgroups called strata then taking separate random samples from each stratum, ensuring every subgroup is represented in the final sample.

Cluster Sample

Sampling method where you divide the entire population into groups called clusters, randomly selecting members some of the clusters, and then collect data from every individuals in the chosen clusters.

Systematic Random Sample

A probability sampling method where you select every kth member from an ordered list after choosing a random starting point.

Undercoverage

A type of sampling bias that occurs when some groups in the population are left out or underrepresented in the sampling process, so they have little or no change of being selected.

Nonresponse Bias

The distortion in survey results that happens when the people who choose no to respond are systematically different from those who do respond. No longer accurately represents the full population.

Response Bias

A tendency for survey respondents to give inaccurate or untruthful answers, causing data to systematically duffer form the true values. Usually caused by social pressures, who asks the question, or the way it is worded.

Observational Study vs. Experiment

Study- A type of statistical study where the researcher collects data by observing subjects without assigning treatments or manipulating any variables.

Experiment- Deliberately imposes specific treatments on experimental units or subjects to measure their response, active manipulation and controlled.

Treatments

Specific conditions or combination of specific values (levels) applied in an experiment.

Confounding Variable

A variable that is associated with both the explanatory and response variables, making it impossible to tell whether the observed effect is caused by the explanatory variable of the confounder. Creates misleading picture of the relationships between the variables you actually care about.

Placebo Effect

A measurable change in a subject’s response variable caused not by the actual treatment but by the subject’s belief or expectation that they are receiving a treatment.

Blinding

An experiment where neither the subjects not the researchers who interact with them know which treatment each subject is receiving. Prevents both groups from unconsciously influencing the results.

Randomized Block Design

An experimental design where subjects are first sorted in to groups (blocks) that share similar characteristics, then treatments are randomly assigned within each block. Reduces the effect of that characteristic on the result, making it easier to detect the true effect of the treatment.

Matched Pairs Design

An experimental design where subjects are grouped into pairs that share similar characteristics, and each member of the pair is randomly assigned to a different treatment. Each person serves as their own control.