The answer is: Longintudinal studies
Longintudinal studies refers to the studies that conducting by observing one single variable at a prolonged period of time.
Before tools for computational psychiatry was invented, the ways that psyciatrist can used to collect the data from the test subject is very limited. Because of this, the need to rely on their own senses to observe the subject for a long period of time in order to collect the data.
