CRIM_220_-_Lecture_6_-_QEs_and_Sampling

Quasi-experimental designs

Research designs that do not involve random assignment or manipulation of the independent variable.

Internal validity

The degree to which a study accurately establishes a cause-and-effect relationship.

Non-equivalent groups

Groups that are not randomly assigned, resulting in potential differences between them.

Time-series designs

Research designs that involve multiple observations over time to study a phenomenon.

Static-group comparison

A quasi-experiment comparing a treatment group to a comparison group without randomization.

Pretest-posttest nonequivalent control group

A design that includes a pretest before the treatment and a posttest after the treatment, comparing two non-equivalent groups.

One-group pretest-posttest design

A design where one group is measured before and after treatment, but lacks a comparison group.

Interrupted time-series design

A design that involves measuring a dependent variable at multiple time points before and after an independent variable is introduced.

Sampling

The process of selecting a subset of individuals from a larger population.

Probability sampling

Sampling methods where each member of the population has a known and equal chance of being selected.

Non-probability sampling

Sampling methods where the probability of selection is unknown and is often based on the researcher's judgment.

Stratified random sampling

A method ensuring representation from identified subgroups within the population.

Convenience sampling

Sampling based on the ease of access to participants, without a structured population framework.

Quota sampling

A non-probability sampling method ensuring a fixed proportion of specific characteristics in the sample.

Snowball sampling

A method where existing participants recruit future subjects from their acquaintances to participate in the study.

Sampling error

The discrepancy between a sample statistic and the corresponding population parameter.

Estimation of parameter from statistic

The process of inferring population characteristics based on sample data.

Confidence levels

Statistical measures that estimate the probability that a given statistical estimate will fall within a specified range.

True experimental designs

Research designs that involve random assignment to treatment and control groups, allowing for causal inferences.

Random assignment

The process of randomly assigning participants to different groups to ensure each group is similar before treatment.

Control group

A group in an experiment that does not receive the treatment and is used for comparison.

Dependent variable

The variable that is measured and affected in response to changes in the independent variable.

Independent variable

The variable that is manipulated or changed in an experiment to observe its effects on the dependent variable.

Effect size

A quantitative measure of the magnitude of a phenomenon, indicating the strength of a relationship or treatment effect.

Random sampling

A sampling technique where each member of the population has an equal chance of being selected, aiding in the representativeness of a sample.

Longitudinal study

A study that follows the same subjects over a period of time, observing changes and developments.

Cross-sectional study

A study that analyzes data from a population at a specific point in time, providing a snapshot without temporal dimension.