Sampling theory

4-I agree with you that Sampling theory was developed to determine the most effective way of acquiring a sample that accurately reflects the population under study. A sample is the selected group of people or elements in a study. The sample selected should represent an identified population or a particular group of individuals or elements that is the focus of the research. And  to add that Sampling theory is also  the study of the relationship that exist between a target population and the samples that are drawn from the population and this only applies to samples that are drawn randomly.  The main concepts of the sampling theory are the target population, representative samples and sampling plans or methods.

Target population is also known as research universe.  The subject of investigation is the whole statistical data.  A sampling plan normally states methods that are to be used to collect random samples from the population in such a way that there is very minimal to zero biasness.  The methods can use random probability sampling techniques.

The following steps are normally involved when developing a sampling plan, they are as follows,

Identification of parameters to be measured.

Designing intervals of measurement.

Selection of sample sizes

Establishment of data storage formats

Assigning roles and responsible to the research teams.

Generalizability is the process of extrapolating the research findings of a sample population to the general population.  The reason behind it, that the sample population that was selected represented the entire population. As such the research could extrapolate the findings and make a conclusion that represents the entire population.

References:

Chambers, R, Chambers R, L & Skinner, C(2003), Analysis of Survey Data. Retrieved from https://www.powells.com/books/analysis.

Korn, E & Graubard, B. (1999) Analysis of Health Surveys. Retrieved from online library .wiley.com.

 

5-‘In theoretical sampling the sample is ‘not selected from the population based on certain variables prior to the study, rather the initial sample is determined to examine the phenomena where it is found to exist. Then, data collection is guided by a sampling strategy called theoretical sampling. This implies that the researcher starts the study with a sample where the phenomenon occurs and then the next stage of data collection is when theoretical sampling begins. Theoretical sampling is the process of data collection whereby the researcher simultaneously collects, codes and analyses the data to decide what data to collect next. Deciding where to sample next according to emerging codes and categories is theoretical sampling” (Coyne, 1997)

An example might include a group of Caucasian men, ages 60-70, diagnosis of heart failure. The study could include the effects of following a sodium and fluid restriction diet and the impact on the men’s health.

“Generalizability is a measure of how useful the results of a study are for a broader group of people or situations. If the results of a study are broadly applicable to many different types of people or situations, the study is said to have good generalizability. If the results can only be applied to a very narrow population or in a very specific situation, the results have poor generalizability” (Hydrocephalus, n.d)

Coyne, I. (1997). Sampling in qualitative research. Purposeful and theoretical sampling; merging or clear

boundaries? Journal of Advanced Nursing, 26(3), 623-630. Retrieved 9 13, 2018, from

http://corcom300-

s12-lay.wikispaces.umb.edu/file/view/article_sampling_qualitative.pdf

Hydrocephalus Association, n.d. Research 101:  Generalizability. Retrieved 9 13, 2018, from

 

6-I agree with you that Sampling is choosing a determinate variable within a research study.  There are many steps in the process of choosing a sample.” Sampling theory was developed to determine the most effective way of acquiring a sample that accurately reflects the population under study. And  to add that Sampling also entails studying a chosen group of people who represents a larger population.  Sampling theory describes two sampling domains: probability sampling and non-probability sampling.   In probability sampling findings can be generalized to the given population while in non-probability sampling, findings can only be generalized to the place the study was done. (Summers, 1991)

Probability sampling methods are systemic sampling, random sampling and cluster sampling while non-probability sampling methods involves theoretical sampling, purposeful sampling, network sampling and convenience sampling. (Thompson,1999)

The textbook defines generalizability as the extendibility “of the implication of the findings from the samples or situation that was studied to a larger population or situation.” (Grove et al. 2015).  In my opinion, findings from a health-related research study should only be generated if it is performed among many people and is proven to be accurate multiple times.

References:

Grove, S, Gray, J & Burns, N.( 2015) Understanding Nursing Research, 6th edition.

Summers, S(1991) Selecting a sample from a research study. Post Anesthesia Nurse. Retrieved from http://ebn.bmj.com.

Thompson, C(1999) .If you could just provide me with a sample: examining sampling in qualitative and quantitative research papers. Retrieved from http://ebn.bmj.com.