# Calculators

#### A/B Test Calculator

Compare two independent proportions for A/B testing or comparing completion rates or conversion rates for small and large sample sizes.

#### Confidence Interval Calculator

Compute confidence intervals around continuous data using either raw or summary data.

#### Compare 2 Small Sample Completion Rates (Fisher Exact Test)

Use this calculator to determine if there is a significant difference between 2 small sample completion rates.

#### One Sample Proportion Calculator

Use this calculator to generate both a one-sample confidence interval and to test against a critera or benchmark.

#### Sample Size Calculator for a Completion Rate

Use this calculator to understand how sample size changes will affect the confidence interval around a completion rate.

#### Interactive Graph of the Standard Normal Curve

Hover over the normal curve to display the area and z-score.To enter specific values use the Z-Score to Percentile Calculator or the Percentile to Z-Score Calculator.

#### Percentile to Z-Score Calculator

Enter the area under the normal curve (a proportion between 0 & 1) and get the Z-critical value, one-sided or two-sided.

#### Z-Score to Percentile Calculator

Enter a z-critical value and get the area under the normal curve (a percentage). Selecting two-sided provides the area above Z and below -Z.

#### Sample Size Calculator for Discovering Problems in a User Interface

This calculator produces an estimate of the number of users needed to discover the specified percent of total problems. It uses the Good-Turing and Normalization procedure.

#### Graph and Calculator for Confidence Intervals for Task Times

This calculator takes raw task times, them using the Natural Logarithm and computes a confidence interval. The values are displayed in the dot-plots graphs.

#### One Sample Proportion Calculator

Use this calculator to generate both a one-sample confidence interval and to test against a critera or benchmark.

#### Sample Size Calculator for a Completion Rate

Use this calculator to understand how sample size changes will affect the confidence interval around a completion rate.

#### Sample Size Calculator for Discovering Problems in a User Interface

This calculator produces an estimate of the number of users needed to discover the specified percent of total problems. It uses the Good-Turing and Normalization procedure.

#### A/B Test Calculator

Compare two independent proportions for A/B testing or comparing completion rates or conversion rates for small and large sample sizes.

#### Compare 2 Small Sample Completion Rates (Fisher Exact Test)

Use this calculator to determine if there is a significant difference between 2 small sample completion rates.

#### Percentile to Z-Score Calculator

Enter the area under the normal curve (a proportion between 0 & 1) and get the Z-critical value, one-sided or two-sided.

#### Z-Score to Percentile Calculator

Enter a z-critical value and get the area under the normal curve (a percentage). Selecting two-sided provides the area above Z and below -Z.

#### Confidence Interval Calculator

Compute confidence intervals around continuous data using either raw or summary data.

#### Interactive Graph of the Standard Normal Curve

Hover over the normal curve to display the area and z-score.To enter specific values use the Z-Score to Percentile Calculator or the Percentile to Z-Score Calculator.

#### Graph and Calculator for Confidence Intervals for Task Times

This calculator takes raw task times, them using the Natural Logarithm and computes a confidence interval. The values are displayed in the dot-plots graphs.