Threats To Internal Validity

History

occurs when external, unexpected events happening between pretest and post-test—unrelated to the study's intervention—influence participants' behavior and obscure true experimental results

maturation

refers to changes in participants over time, such as aging or development, that may affect their responses, independent of the intervention

testing

refers to the effects on participants' performance due to repeated exposure to a test or measurement, which may not reflect the intervention's true impact

instrumentation

refers to changes in the measurement instruments or procedures used during the study, which may lead to inconsistencies in data collection and affect the results.

order

refers to effects that arise from the sequence in which treatments or measurements are administered in a study. This can lead to biases as prior experiences may influence subsequent responses.

selection

refers to biases that occur when the participants selected for a study are not representative of the larger population, potentially affecting the generalizability of the findings.

attrition

refers to the loss of participants from a study over time, which can affect the validity of the results if the individuals who drop out differ significantly from those who remain.

demand characteristics

are cues or signals in a research study that may influence participants' behavior and responses, often leading them to alter their behavior to align with perceived expectations.

observer bias

causing researchers to unconsciously influence, record, or interpret data to match their expectations

placebo effect

it can cause participants to show improvement due to expectations rather than the actual intervention, confounding results