Observational research is a type of study design where researchers observe the effect of an intervention, a risk, a diagnostic test, or treatment, without trying to manipulate who is, or who isn't, exposed to it. This differs from an experimental study, where scientists manipulate who is exposed to the treatment or intervention, by having a control group and an experimental group.

Observational research is often used to answer research questions based purely on what the researcher observes. There is no interference or manipulation of the research subjects, and no control and treatment groups.

In the design process, observational research is considered the most appropriate empirical procedure and the objects and functions it researches serve design most effectively.

There are several types of observational research, including:

1. Naturalistic observation: This involves studying the user “in the wild” without manipulating variables or intervening in any way. This type of observation provides a realistic snapshot of behavior as it occurs in real-life settings, thereby enhancing ecological validity.

2. Controlled observation: This involves capturing the behaviors of research participants in an isolated environment. Researchers may utilize a case-control study when they want to establish the causation of a particular phenomenon.

3. Structured observation: This is similar to naturalistic observation, but the emphasis is on gathering quantitative rather than qualitative data. In structured observation, researchers are interested in a limited set of behaviors, allowing them to quantify the behaviors they are observing.

Observational research has several advantages. It can provide information about difficult-to-analyze topics in a low-cost, efficient manner. It allows you to study subjects that cannot be randomized safely, efficiently, or ethically. However, it also has some disadvantages. There is a high risk of observer bias and undetected confounding variables. They cannot make statements about the safety or efficacy of the intervention or treatment they study, only observe reactions to it. Therefore, they offer less satisfying results than other methods.

In the context of design, observational studies can be used to understand how users interact with a product, which can be valuable for informing later, larger-scale designs.