A number of different methods allow flexibility in the way we conduct psychological research. In experimental studies the variables are controlled and manipulated to give the maximum precision to our observations. The drawback of such control is that we cannot know how well the behavior observed in the artificially controlled environment will generalize to everyday life. In an observational study, we systematically observe behavior in its natural environment. We sacrifice a degree of control and precision for naturalism. Cross-sectional studies assess behavior at one point in time. Longitudinal studies observe behavior over a period of time, sometimes over decades. In quantitative studies, behavior is quantified into numbers. Even though quantitative research is the most common form of psychological research, qualitative research has gained more attention recently. This involves careful observation without the use of numbers.