Everson, Michael; etal. (2002-03-20). "L2/02-141: Uralic Phonetic Alphabet characters for the UCS" (PDF). Archived (PDF) from the original on 2018-02-19 . Retrieved 2018-03-24. Ti Alkire & Carol Rosen, Romance Languages: A Historical Introduction (Cambridge: Cambridge University Press, 2010), 61.

where x is the raw score, μ is the population mean, and σ is the population standard deviation. For a sample, the formula is similar, except that the sample mean and population standard deviation are used instead of the population mean and population standard deviation. The Semitic symbol was the seventh letter, named zayin, which meant "weapon" or "sword". It represented either the sound / z/ as in English and French, or possibly more like / dz/ (as in Italian zeta, zero).

The z-score, also referred to as standard score, z-value, and normal score, among other things, is a dimensionless quantity that is used to indicate the signed, fractional, number of standard deviations by which an event is above the mean value being measured. Values above the mean have positive z-scores, while values below the mean have negative z-scores. The Etruscan letter Z was derived from the Phoenician alphabet, most probably through the Greek alphabet used on the island of Ischia. In Etruscan, this letter may have represented / ts/. Henry George Liddell; Robert Scott. "ζῆτα". An Intermediate Greek–English Lexicon. Archived from the original on March 6, 2020 . Retrieved July 23, 2016. One early use of "zee": Lye, Thomas (1969) [2nd ed., London, 1677]. A new spelling book, 1677. Menston, (Yorkshire) Scolar Press. p. 24. LCCN 70407159. Zee Za-cha-ry, Zion, zeal Among non-European languages that have adopted the Latin alphabet, ⟨z⟩ usually stands for [z], such as in Azerbaijani, Igbo, Indonesian, Shona, Swahili, Tatar, Turkish, and Zulu. ⟨z⟩ represents [ d͡z] in Northern Sami and Inari Sami. In Turkmen, ⟨z⟩ represents [ ð].

Castilian Spanish uses the letter to represent / θ/ (as English ⟨th⟩ in thing), though in other dialects ( Latin American, Andalusian) this sound has merged with / s/. Before voiced consonants, the sound is voiced to [ ð] or [ z], sometimes debbucalized to [ ɦ] (as in the surname Guzmán [ɡuðˈman], [ɡuzˈman] or [ɡuɦˈman]). This is the only context in which ⟨z⟩ can represent a voiced sibilant [ z] in Spanish, though ⟨s⟩ also represents [ z] (or [ ɦ], depending on the dialect) in this environment. Constable, Peter (2003-09-30). "L2/03-174R2: Proposal to Encode Phonetic Symbols with Middle Tilde in the UCS" (PDF). Archived (PDF) from the original on 2017-10-11 . Retrieved 2018-03-24. Latin letter z with a hook, intended for the transcription of Middle High German, for instances of the letter z with a sound value of /s/. z⟩ stands for a voiced alveolar or voiced dental sibilant / z/, in Albanian, Breton, Czech, Dutch, French, Hungarian, Latvian, Lithuanian, Romanian, Serbo-Croatian, Slovak, and the International Phonetic Alphabet. It stands for / t͡s/ in Chinese pinyin and Jyutping, Finnish (occurs in loanwords only), and German, and is likewise expressed /ts/ in Old Norse. In Italian, it represents two phonemes, / t͡s/ and / d͡z/. In Portuguese, it stands for / z/ in most cases, but also for / s/ or / ʃ/ (depending on the regional variant) at the end of syllables. In Basque, it represents the sound / s/.

Other languages spell the letter's name in a similar way: zeta in Italian, Basque, and Spanish, seta in Icelandic (no longer part of its alphabet but found in personal names), zê in Portuguese, zäta in Swedish, zæt in Danish, zet in Dutch, Indonesian, Polish, Romanian, and Czech, Zett in German (capitalised as a noun), zett in Norwegian, zède in French, zetto ( ゼット) in Japanese, and zét in Vietnamese. Several languages render it as / ts/ or / dz/, e.g. tseta /tseta/ or more rarely tset /tset/ in Finnish (sometimes dropping the first t altogether; /seta/, or /set/ the latter of which is not very commonplace). In Standard Chinese pinyin, the name of the letter Z is pronounced [tsɨ], as in "zi", although the English zed and zee have become very common. In Esperanto the name of the letter Z is pronounced /zo/. a b Constable, Peter (2004-04-19). "L2/04-132 Proposal to add additional phonetic characters to the UCS" (PDF). Archived (PDF) from the original on 2017-10-11 . Retrieved 2018-03-24.