Often called quartz topaz, citrine topaz, or topaz, all of which are misleading. It is yellow, amber, to amber brown. While a pleasing stone in terms of colour, and fairly durable, citrine is slightly softer and has less brilliance than precious topaz.
In this respect, a cohort study is often interchangeable with the term naturalistic observation. There are two main sub-types of cohort study, the retrospective and the prospective cohort study. The major difference between the two is that the retrospective looks at phenomena that have already happened, whilst the prospective type starts from the present. . The retrospective case study is historical in nature.
There are many ways to categorize the different types of research. For example, research in different fields can be called different types of research, such as scientific research, social research, medical research, environmental research and so forth. The research methods that are used and purposes of the research also can be used to categorize the different types of research. A few of these types of research include quantitative and qualitative research; observational and experimental research; and basic, applied and developmental research.