Getting The Sample Size. To find the right z-score to use refer to the table below. Some researchers do however support a rule of thumb when using the sample size.
N population size e Margin of error percentage in decimal form z z-score. Samples can be vague or specific. However the relationship is not linear ie doubling the sample size does not halve the confidence interval.
Sample size is a market research term used for defining the number of individuals included to conduct research.
Its equation can be derived by using population size the critical value of the normal distribution sample proportion and margin of error. For example you may want to know what people within the 18-25 age range think of your product. One approach is to use the entire population as the sample. As such the determination of the appropriate sample size is one of the recurrent problems in statistical analysis.
