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About Sample Size Formula
- Sample size formula helps us to find accurate sample size through the difference between population and sample. Find, the number of observations in a given sample population is known as sample size. Since it is not possible to survey the whole population, we take a sample from the population and then conduct a survey or research. The sample size can be represented by “n” or “N”. Where it can be written as “SS”. Now take a look at the sample size formula along with a few solved examples.
- What is Sample Size Formula?
- Sample size formula is determined in the two different steps. First, we calculate the sample size for an infinite population and second we adjust the sample size to the required population. The sample size formula can be written as:
- Formula 1: Sample size for infinite population
- Formula 2: Adjusted sample size
- Adjusted Sample Size =
- where,
- S denotes sample size for infinite population
- Z denotes Z score
- P denotes population proportion ( Assumed as 50% or 0.5)
- M denotes the Margin of error
Note: Z score is found based on the confidence level.
Confidence Level: Probability that the value of the parameter falls within a specified range of the values. As per the example, for a 95% confidence level Z score is 1.960.
The margin of error: It is defined as a small amount which is allowed in case of miscalculation or change of circumstances. Generally, the margin of error is taken as 5% or 0.05.
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