Calculates the sample size for a survey (proportion) or calculates the sample size for a normal confidence interval.

Fill the **proportion** **or** the **Standard deviation (σ)**.

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To get the confidence interval of an estimate value ± MOE

leave empty for an infinite population. When the sample size is less then 5% of the entire population you can assume infinite population.

Shapiro Wilk test

Outliers count: ,based on the Tukey's fences method, k=1.5

**Information**

Calculates the sample size to achieve the required **confidence interval**.__Example__

What sample size should you use for a survey in a city with a population of 120,000 people?

You want to have a confidence level of 95%.

The confidence interval should be ± 0.05 (± 5%).

Survey question: "what party will you vote?"__Solution__**Confidence level = 0.95** .

If you don't know what proportions to expect you should assume the **worth case** meaning the largest standard deviation.

The largest standard deviation for a proportion is for **Proportion = 0.5**, which means that one party will gain 50% of the votes.

Population standard deviation (σ) - leave empty as it will be calculated from the proportion.**Margin of error (MOE) = 120,000 .****Population (N) = 120,000 .**

The following R code should produce the same results.