▁to ▁help ▁them ▁select ▁the ▁final ▁ 2 4 ▁strength s ▁for ▁the ▁CSV ▁( see ▁CSV ▁for ▁complete ▁list ▁of ▁criteria ). ▁ ▁Appro xim ately ▁half ▁of ▁the ▁strength s ▁included ▁in ▁the ▁CSV ▁meet ▁all ▁ 1 0 ▁criteria , ▁and ▁half ▁do ▁not . ▁ ▁By ▁looking ▁for ▁similar ities ▁between ▁candidate ▁strength s , ▁the ▁research ers ▁distributed ▁ 2 4 ▁character ▁strength s ▁between ▁six ▁virtue ▁categories . ▁ ▁Only ▁after ▁creating ▁this ▁a ▁pri ori ▁organization ▁of ▁tra its , ▁the ▁research ers ▁performed , ▁“ an ▁expl or atory ▁factor ▁analysis ▁of ▁scale ▁scores ▁using ▁var im ax ▁rotation ,” ▁( p .   6 3 2 ) ▁from ▁which ▁five ▁factors ▁emer ged . ▁ ▁Pet erson ▁& ▁Sel ig man ▁state ▁that ▁they ▁are ▁not ▁as ▁concerned ▁with ▁how ▁the ▁ 2 4 ▁strength s ▁are ▁grouped ▁into ▁virtue ▁clusters ▁because , ▁in ▁the ▁end , ▁these ▁tra its ▁are ▁mixed ▁together ▁to ▁form ▁the ▁character ▁of ▁a ▁person . ▁ ▁Valid ity ▁and ▁reli ability ▁ ▁Pet erson ▁and ▁Sel ig man ▁state ▁that ▁all ▁character ▁strength s ▁must ▁be ▁meas urable . ▁ ▁Of ▁the ▁ 2 4 ▁strength s , ▁most ▁can ▁be ▁ass essed ▁using ▁self - report ▁question na ires , ▁behavior al ▁observation , ▁peer - report ▁methods ▁and ▁clin ical ▁inter views . ▁ ▁Three ▁strength s , ▁however , ▁have ▁yet ▁to ▁be ▁reli ably ▁ass essed : ▁hum ility , ▁mod esty ▁and ▁bra