ABSTRACT
Asyoulearnedinthepreviouschapter,thefamilyofstatisticscalled averagesindicateswherethecenterofadistributionlies.Forthedistributionofemotionalhealthscoresforagroupofadolescentmalesinafoster carehome(seepage13ofthisbook),themeanscoreis43.3.Forthenationalnormgrouponwhichtheemotionalhealthscalewasstandardized, themeanis50.0.Thus,weknowthatthegroupinthefostercarehomeis lowerontheaveragethanthenationalnormgroup.However,supposethat thisisallthatweknow.Thatis,supposewereadareportandweregiven onlythemeanswithoutthefrequencydistribution,polygon,histogram,or anyotherstatistics.Wewouldbemissingalotofimportantinformation, wouldn'twe?Forexample,thedistributiononpage13showsthatasubstantialpercentageofthefosterhomeboyshadscoresashighasorhigher thanthenationalmeanof50.Thus,clearlyifwearegoingtoreportthe mean(withoutafrequencydistribution,polygon,orhistogram),we'llneed tosupplementitwithanadditionalstatisticthatindicateshowspreadout thescoresarearoundtheirmeanof43.3.Inthischapter,wewillexamine thestatisticthatismostwidelyusedforthispurpose.
