In observational research, the observer becomes an active participant in the research setting.
The entire group of people, events or situations which is of interest in the research. As it is usual not possible to gather data from every member of a population (though see Census), a sample has to be drawn.
Research undertaken following the introduction of the independent variable (e.g. after the intervention or treatment has occurred).
Research undertaken prior to the introduction of the independent variable (e.g. after the intervention or treatment has occurred).
The ability of a tool or instrument to predict a future state on some external criterion (e.g. how well a test taken at a job interview will predict how well a candidate will perform when doing the job).
New research undertaken by the researcher which involves gathering and analysing new data.
A sample that has been selected using a random sampling procedure. In this type of sampling every member of the population has an equal chance of being selected for the sample.