WhatisaNormalCurveEquivalentScore?TheNormalCurveEquivalent,orNCE,isawayofmeasuringwhereastudentfallsalongthenormalcurve.ThenumbersontheNCElinerunfrom0to100,similartopercentileranks,whichindicateanindividualstudent'srank,orhowmanystudentsoutofahundredhadalowerscore.NCEscoreshaveamajoradvantageoverpercentilerankscoresinthattheycanbeaveraged.Thatisanimportantcharacteristicwhenstudyingoverallschoolperformance,andinparticular,inmeasuringschoolwidegainsandlossesinstudentachievement.

Inanormallydistributedpopulation,ifallstudentsweretomakeexactlyoneyearofprogressafteroneyearofinstruction,thentheirNCEscoreswouldremainexactlythesameandtheirNCEgainwouldbezero,eventhoughtheirrawscores(i.e.thenumberofquestionstheyansweredcorrectly)increased.Somestudentswillmakemorethanayear'sprogressinthattimeandwillhaveanetgainintheNCEscore,whichmeansthatthosestudentshavelearnedmore,oratleasthavemademoreprogressintheareastested,thanthegeneralpopulation.Otherstudents,whilemakingprogressintheirskills,mayprogressmoreslowlythanthegeneralpopulationandwillshowanetlossintheirNCEranks.

Aswithmanyotherscalesrelatedtothenormalcurve,theaverageNCE,bydefinition,is50.Ifallstudentsimproveintheirperformance,themean,orNCE50,willrepresentahigherrawscore.ThestandarddeviationofNCEissetat21.06.NCEweredevelopedforprogramevaluationandareusuallythechoiceforsignificancetesting.