Data collection refers to a systematic way of obtaining, observing, measuring, and analyzing accurate information. Observational studies are one of the most widely used methods of data collection. It involves collecting data by observing the behavior and physical characteristics of a sample without making any modifications to the sample.

An astronomer viewing the motion and brightness of stars in the sky and recording the data is an example of observational data collection. A botanist recording the data of daily plant growth also falls into the category of observational data collection. In both cases, no external modification is made to the sample in the process of data collection. Similarly, conducting a survey of the population of a country in a year requires the collection of data using the observational method.

The main advantage of this method is that samples are collected from the subjects’ natural environment. Also, the method is a direct method; that is, it does not require any modifications. Most often, the non-verbal cues, behavior, or patterns are used to draw observations to provide insight into the subjects in their natural environment. However, the observational method provides no control sample, which might provide data in the absence of the observer.