Z-Score Calculator

Numero di deviazioni standard che un valore X dista dalla media μ. z = (X - μ) / σ. Permette di confrontare valori da distribuzioni diverse o calcolare la probabilità di un valore.

Probabilità di osservare un valore almeno estremo come quello ottenuto, assumendo l'ipotesi nulla vera. p < 0.05 tipicamente indica significatività statistica.

It is the number of standard deviations that separate a value from the mean. It lets you compare measurements coming from different distributions, by bringing them all onto one scale.

It says how likely it is to see a value this extreme if the starting hypothesis were true. Below the threshold you have fixed, usually five per cent, the result is called significant.

With one tail you look at the departure in a single direction, with two tails in both. The two tailed test is the more cautious one, because it splits the threshold between the two sides.