## Statistical Significance Calculator

Use this calculator to determine whether two percentages are statistically significantly different or not.

Number of Surveys – Sample 1 | |

Observed % – Sample 1 (written as a number between 0 and 100; i.e., 70% = 70) | |

Number of Surveys – Sample 2 | |

Observed % – Sample 2 (written as a number between 0 and 100; i.e., 70% = 70) | |

Confidence Interval ± | |

Significance = |

## Sample Size to Achieve Desired Error Rate

Use this calculator to determine how many surveys you need to achieve a desired confidence interval (or margin of error). A confidence interval, or margin of error, tells you the range that likely contains the true value of a population. You may have seen it as a plus or minus amount reported with poll results. For example, if your confidence interval is 6, and 70% of your sample picks an answer, you can be sure that if you asked everyone in the population, you would get an answer of between 64% and 76% (70% ± 6%).

**N [universe]**: The total number of people your sample represents

**Confidence Level:** A confidence level tells you how often the true percentage of the population falls within the confidence interval. Using a 95% confidence level means you can be 95% certain, and a 99% confidence level means you can be 99% certain that the true percentage of the population is within the confidence interval.

Picking a higher confidence level means your confidence interval will be larger. Picking a lower confidence level means the confidence interval will be smaller.

If you don’t know what to pick, a 95% confidence level is commonly used.

N [universe] | |

z [confidence interval in decimal form] | |

Confidence Level | |

Sample Needed |

## Error Rate Calculator

Use this calculator to determine your confidence interval. A confidence interval, or margin of error, tells you the range that likely contains the true value of a population. You may have seen it as a plus or minus amount reported with poll results. For example, if your confidence interval is 6, and 70% of your sample picks an answer, you can be sure that if you asked everyone in the population, you would get an answer of between 64% and 76% (70% ± 6%).

**n [sample]**: How many surveys were completed

**N [universe]:** How many people your sample represents

**Confidence Level**: A confidence level tells you how often the true percentage of the population falls within the confidence interval. Using a 95% confidence level means you can be 95% certain, and a 99% confidence level means you can be 99% certain that the true percentage of the population is within the confidence interval.

Picking a higher confidence level means your confidence interval will be larger. Picking a lower confidence level means the confidence interval will be smaller.

If you don’t know what to pick, a 95% confidence level is commonly used.

n [sample] | |

N [universe] | |

Confidence Level: | |

Maximum Error Rate: p=50% q=50% | |

Observed % (written as a number between 0 and 100; i.e., 70%=70) | |

Confidence Interval ± |