A researcher must be theoretically sensitive so that a theory can be conceptualized and formulated as it emerges from the data being collected.
The main question in this method of sampling is this: what groups should the researcher turn to next in the data collection process, and why?
According to Chenitz and Swanson (1986), theoretical sampling emerged with the foundation of grounded theory, which was first developed by Glaser and Strauss in 1967.
Its focus is to develop a theory from continuous comparative analysis of data collected by theoretical sampling.
This basically means that attributes such as gender, ethnicity and even age can't be the basis for a sample.
In theoretical sampling the belief is that researchers need to overcome the tendency to select cases and instances that support their side of the argument.
Instead it states that it would be more beneficial to look out for negative instances and cases which are defined by the theory that we are working with.
Finally flexibility is also allowed when the researcher finds unexpected generalization and wants to look into deviant cases.
[12] In theoretical sampling, there are two main criteria for initial data collection, general sociological perspective and problem area.
Collection criteria for the future cannot be planned in advance as the criterion emerges as the theory evolves.
The main criterion is that the data collected should apply to a particular category or property, irrespective of the differences or similarities.
Population scope Also differences and similarities can either be maximised or minimised, depending on the type of groups being compared.
When the researcher minimises differences among groups, s/he is able to establish a definite set of conditions under which a category exists.
The ability to generate an extensive understanding of a completely well theory defined in any field through research takes in the account of theoretical sampling.
For example, how confident men handle prospective marks or how policemen act toward people of African descent or what happens to students in medical school that turns them into doctors, is dependent on the theoretical framework that the researcher arrives with.
[16] Theoretical sampling helps in exploring various hibernating research questions that are eventually evident in the data collection as a theory.
Theoretical sampling is considered to be purpose driven and it explicitly carries out its function on the basis of an emerging theory.
Saturation point determines the sample size in qualitative research as it indicates that adequate data has been collected for a detailed analysis.
For example, in many phenomenographic studies, theoretical saturation is often reached after 15 to 30 participants,[20] whereas other methods may require far fewer, or greater, numbers.
Then I wished to observe on a service where staff expectations of terminality were great but where patients might or might not be, and where dying tended to be slow.