Statistics and Data

Start with what you want to know about your data. To describe a data set, the Mean Median Mode Calculator gives the center and range. The Standard Deviation Calculator shows how spread out the values are. Use the sample result when your data comes from part of a group, and the population result when you have every value.

For chances and counting, the Combination and Permutation Calculator tells you how many ways items can be chosen. Order matters for permutations but not for combinations. Picking 3 items from 10 gives 120 combinations but 720 permutations. The Probability Calculator handles single events, conditional probability and Bayes theorem.

For surveys and test scores, the Normal Distribution Calculator turns a z-score into a percentile and shades the area on a bell curve. The Sample Size Calculator shows how many responses you need. At 95% confidence and a 5% margin of error, a large population needs about 385 responses.