Root Mean Square Calculator

RMS shown next to the plain mean, because on signed data the mean collapses to nearly zero while the RMS holds the magnitude that actually matters. Also gives the crest factor, the sum of squares and each value's share of it.

Summarising a dataset before drawing conclusions from it, checking whether a difference between two groups is real, and putting an interval around an estimate.

Reading a p-value as the probability that the hypothesis is wrong. It is the probability of seeing data at least this extreme if the null were true — a different statement, and a much weaker one.

They sit next to each other but answer different questions: Square root calculator is the one to open when you need it to compute the square root of a number, plus its square. Pick whichever matches what you're starting from — both are free.

Average Deviation Calculator (mean absolute deviation) is the closest one after this: The average absolute deviation from the mean AND from the median — the median is the point that minimises it, which is worth seeing. Every |x − centre| is listed, and the standard deviation sits beside it for contrast: squaring makes SD react hard to a single outlier while the average deviation barely moves. The outlier preset is built to show exactly that.

Sample Mean Calculator and Chi-Square Test Calculator — they come up in the same task often enough to be worth a second tab.

Distributions and test statistics are computed from their standard definitions, not from a lookup table, so results carry more digits than a printed table would. The assumptions each test makes are stated with it.