I am yet to start my research study - Factors influencing Investment preference, finalized on the questionnaire.
The total population size is around 4000 no's. How to decide on sample?.
In a website it asks for confidence interval apart from confidence levels. If we assume 95% confidence level, what would be our confidence interval?
One of my friend says that through pilot study we can find out confidence intervals and then we can decide on the samples. Is that correct?
Please give me your guidance on this.
1. Procedure to decide sample size
2. What is meant by confidence interval
Sir you can use 'Yamane' Sample size formula. You can choose level of Significance as per your convenience
Pilot study
Saunders et al., (2007) state that prior to using the questionnaire to collect data it should be pilot tested. Saunders et al., (2007) point out the purpose of the pilot test is to refine the questionnaire so that the respondents will have no problems in answering the questions and also there will be no problems in recording the data
Fink (2003b) as cited in Saunders et al., (2007) state that the minimum number for a pilot study is 10.
For the main study
Sekaran (2003) wrote:
Roscoe (1975) proposes the following rules of thumb for determining sample size:
1. Sample sizes larger than 30 and less than 500 are appropriate for most research.
2. Where samples are to be broken into subsamples; (male/females, juniors/
seniors, etc.), a minimum sample size of 30 for each category is necessary.
3. In multivariate research (including multiple regression analyses), the sample size should be several times (preferably 10 times or more) as large as the number of variables in the study.
4. For simple experimental research with tight experimental controls (matched pairs, etc.), successful research is possible with samples as small as 10 to 20 in size.
References
Sekaran, U., 2003. Research methods for business: A skill building approach. John Wiley & Sons.
Saunders, M.N., 2007. Research methods for business students, 5/e. Pearson Education India.
Dear RG colleague,
Determining the sample sizes involve resource and statistical issues. Usually, researchers regard 100 participants as the minimum sample size when the population is large. However, In most studies the sample size is determined effectively by two factors: (1) the nature of data analysis proposed and (2) estimated response rate.
For example, if you plan to use a linear regression a sample size of 50+ 8K is required, where K is the number of predictors. Some researchers believes it is desirable to have at least 10 respondents for each item being tested in a factor analysis, Further, up to 300 responses is not unusual for Likert scale development according to other researchers.
Another method of calculating the required sample size is using the Power and Sample size program (www.power-analysis.com).
Regards,
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