For my doctoral research, I will be conducting two parallel qualitative studies using interviews: one with persons with intellectual and developmental disabilities, and the other with family caregivers of persons with intellectual and developmental disabilities. I will be interviewing both populations about decision-making about a specific health-related topic. I am having difficulties determining a sample size for my dissertation proposal. Qualitative methods books do not specify a sample size, but rather speak of data saturation. However, as this research is time limited, I do not know if it will be feasible to gather data until saturation. I am therefore encouraged to specify a specific sample size that I aim to attain. Based on your experiences, do you have any recommendations or literature to share on the topic? Thank you kindly!
Yes, data saturation is the key for determination of sample size. Please refer to the following article:
https://www.statisticssolutions.com/qualitative-sample-size/
Hope it helps. Best wishes.
Dear Madam Lynne A. Potvin Qualitative research experts argue that there is no straightforward answer to the question of ‘how many’ and that sample size is contingent on a number some study reported that 30-50 number is good enough for a qualitative study
You may go through to this link
Article Characterising and justifying sample size sufficiency in int...
A sample of 20 - 50 respondents is even bigger for a qualitative study. You can get your PhD by studying one respondent (if your design is biography). Less than 15 respondents are still credible for a qualitative study. The concern is not on quantity of subjects but individual views and opinions. Therefore, quantity should not bother you.
In case qualitative study quantity does not matter and even a single participant can be a sample if the study supports. No need to go for any formula for non-probability sampling and you are the best judge to consider a suitable amount based on your objectives and study background.
The problem is selecting the most appropriate participants for your objectives and in that case quantity is not a matter, the right person for your objective is the necessity.
For you to determine your sample size, you need to know the population size from which you draw your sample. This will enable you to get the required sample that will be true representation of the whole population, if not your estimation will be biased.
Qualitative study is still in evolution. The sample depends in study objectives to bring out attitudes, beliefs, practices and behavours relating to the subject matter. In addition it depends on method of qualitative data collection...in depth interviews with individuals or focus group discussions with 6-8 persons per group. To be scientic,it is advisable to have a list of discussion guide....open ended questions to use. This will enable participants views to be comptrehensively collected with some elements of focus .
Go through this article
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2551061/
Really depends on your methodology and method of choice. What‘s the nr. of participants for other studies with similar methodological underpinnings and research design (and possibly even with similar research interests)? Looking forward to hearing more about your project, Lynne!
This paper might help
Article Sample Size in Qualitative Interview Studies: Guided by Info...
general recommendation for in-depth interviews is a sample size of 30
- Badges
- Science topic
- Similar topics
- Mathematics
- Statistics
- Sampling Design
- Sample Size