The calculated sample size for my study is 324 with 5% margin error. However, only 230 respondents responded the questionnaire completely. In this case, what is the margin error for this actual sample size? What is the acceptable margin error in a good research? Any formula to calculate margin error from actual sample size?
Kavitha Selvaraja - Since the calculated sample size for your study is 324 with 5% margin error and only 230 respondents have responded the questionnaire completely. In your case, the non-response rate is 30.02% as out of 324 respondents only 230 have responded. The margin of error can be calculated in two ways, depending on whether you have parameters from a population or statistics from a sample: Margin of error = Critical value x Standard deviation for the population. Margin of error = Critical value x Standard error of the sample.
As sample size increases, the margin of error decreases. As the variability in the population increases, the margin of error increases. As the confidence level increases, the margin of error increases.
You can use the following methods to decrease the margin of error: a) Increase the sample size. Often, the most practical way to decrease the margin of error is to increase the sample size. b) Lower the confidence level.The margin of error decreases as the sample size n increases because the difference between the statistic and the parameter decreases. This is a consequence of the Law of Large Numbers.
There are lots of articles taking about this. I selected one I think it is the best to explain your question. Please see this link below
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.dummies.com/education/math/statistics/how-sample-size-affects-the-margin-of-error/&ved=2ahUKEwiixprLmb7qAhW5aRUIHRm8D3YQFjABegQIDhAF&usg=AOvVaw3I6HqFDbVZHxOl60-gxodI&cshid=1594230292047
The sample size required is partly based on the size of the target population, which you do not give. Assuming it is large (>10,000), then with a sample of 230, you will have approximately +/- 6% margin of error. You can easily find this by using the usual sample size software, and working backwards.
https://www.surveymonkey.com/mp/sample-size-calculator/
Dr Manzoor Hussain , thanks for the comprehensive explanation. Can you share any reference related to this for my reading?
Safaa K. Kadhem thank you so much for the link.
Adrian Esterman thanks a lot for the link
Adrian Esterman May I check if the link you have provided is a recognised link?
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