IC Proporção (normal)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The Proportion Interval Calculator (IC Proporção) is a useful tool for statisticians and researchers. It calculates the confidence interval for the population proportion, based on the desired margin of error and the sample size.
The underlying formula for the calculator is p̂ ± z·√(p̂(1−p̂)/n), where p̂ is the estimated proportion rate, z is the Z-score value corresponding to the desired margin of error, and n is the sample size.
This calculator is especially useful when you need to estimate the population proportion rate with a specified degree of confidence. For instance, if you're researching the customer satisfaction rate in a company and want a 95% confidence level, this calculator can help set a confidence interval for the satisfaction rate.
Remember that the choice of sample size and desired margin of error is critical for the accuracy of the results. Additionally, consider the necessary precautions when working with statistical data, such as the possibility of sampling bias and the need to adjust the formula according to the sample size.
Frequently asked questions
What is the IC Proporção and what is it for?
The IC Proporção is a calculator that estimates the confidence interval for the population proportion based on the desired margin of error and the sample size. It is useful for researchers and statisticians who need to calculate the population proportion rate with a specified degree of confidence.
What are the necessary precautions when using this calculator?
Remember to choose the sample size and desired margin of error carefully, as it affects the accuracy of the results. Additionally, consider the possibility of sampling bias and the need to adjust the formula according to the sample size.
What is the desired margin of error and how do I choose the correct value?
The desired margin of error is the maximum margin of error you are willing to accept. It is expressed as a Z-score, which can be found in normal distribution tables or calculated using a calculator. The correct value depends on the desired confidence level and the sample size.
How can I adjust the formula for the sample size?
If the sample is very small, you need to adjust the formula using a t-distribution instead of a normal distribution. This can affect the precision of the estimation of the population proportion rate.