Ennenjälkeentutkimukset

Ennenjälkeentutkimukset, often translated as "before and after studies" or "pre-post studies," are a common research design used to evaluate the impact of an intervention or event. This research method involves measuring a variable of interest in a group of subjects at two distinct points in time: once before an intervention or event occurs and again after it has taken place. The fundamental principle is to compare the measurements from these two time points to determine if a significant change has occurred.

The "before" measurement serves as a baseline, establishing the initial state of the variable. The "after" measurement is then taken after the intervention has been administered or the event has happened. By analyzing the difference between the pre-intervention and post-intervention scores, researchers can infer whether the intervention had an effect. For example, if a new teaching method is introduced, student test scores would be measured before and after its implementation. A notable improvement in scores after the intervention would suggest its effectiveness.

While straightforward, before-and-after studies have limitations. They are susceptible to threats to internal validity, such as maturation (natural changes in participants over time), history (external events occurring concurrently with the intervention), and regression to the mean (extreme scores tending to move closer to the average on subsequent measurements). To mitigate these threats and strengthen the study's conclusions, researchers may incorporate control groups or more sophisticated designs like interrupted time series analysis. Despite these limitations, before-and-after studies remain a valuable tool for initial evaluations and in situations where more complex designs are not feasible.