For example, I intend to collect interview (Qualitative) data from 10 samples, then proceed to reinforce/verify the collected data through a Likert scale (Quantitative) from a larger sample. What should be the minimum size of the larger group for an acceptable construct?
To achieve high validity and reliability findings you should have a minimum of 150 participants.
Mohamed Haffar thanks for your reply. Does the number, 150 have any statistical theory behind it?
If you want to validate this instrument you use factorial analysis under the SEM method for which a minimum of 200 respondents is required.
Numbers must fit the statistical theory used for data analysis. 50 is an acceptable sample size in survey designs. The acceptable range for validity and reliability measures is always sensitive to sample size (Kim, 2013)
Please see a good sampling text: I recommend these two: https://www.amazon.com/Sampling-Techniques-3rd-William-Cochran/dp/047116240X and
https://www.amazon.com/Elementary-Survey-Sampling-Richard-Scheaffer/dp/0840053614/ref=sr_1_1?keywords=Elementary+survey+sampling&qid=1577867715&s=books&sr=1-1
IMO it makes no sense to quote a single number with no justification and the CLT has no relationship to your question. Your question really is what sample size should I use so that I can trust my survey results. these results also depend on the reliabilty and validity of the instrument you use.Best, David Booth PS also see this:
https://www.google.com/search?q=David+L+Morgan+Construction+of+Likert+scales+Researchgate&rlz=1C1CHBF_enUS874US874&oq=David+L+Morgan+Construction+of+Likert+scales+Researchgate&aqs=chrome..69i57.65437j0j4&sourceid=chrome&ie=UTF-8
Further see: Gr i f f i t h , G . J ., & Jones, K. (2019). Understanding the population structure of
the GHQ-12: Methodological considerations in dimensionally complex
measurement outcomes. Social Science and Medicine, 243, [112638].
https://doi.org/10.1016/j.socscimed.2019.112638 and
David L. Morgans' response here:
https://www.researchgate.net/post/How_to_compare_interview_data_with_questionnaire_data_as_confirmatory_for_the_reliability_of_questionnaire_perceptual_primary_data
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