EXPERIMENT
The most systematic technique of data collection is laboratory experiment, where it is hoped all variables will be able to be controlled by the researcher. Since physics and chemistry (including biochemistry) have gone the farthest in developing the experimental "method", they are (sometimes inappropriately) taken as the gold standard of what science has to be like. Although it should be obvious that great strides have been made in many of the other physical sciences where laboratory experiment is not possible such as astronomy, geology and many areas of biology, the social sciences are sometimes criticized as not being real sciences because they are not based enough on experiment, particularly lab experiment. While small issues of human social behavior can be studied in the artificial setting of a laboratory, attempts to study larger issues have frequently resulted in results that are very controversial because it is not completely clear that all of the variables were actually either being controlled or even measured.
While variables sometimes can be manipulated in a "field" setting, field experiments can be contaminated by factors the experimenter is unaware of.