occup ied ▁with ▁other ▁activities ▁of ▁the ▁program ▁and ▁not ▁give ▁the ▁evaluation ▁complete ▁attention ▁May ▁not ▁be ▁ade qu ately ▁trained ▁as ▁an ▁evalu ator . ▁ ▁External ▁evalu ators ▁Adv antages ▁ ▁More ▁objective ▁of ▁the ▁process , ▁offers ▁new ▁pers pect ives , ▁different ▁angles ▁to ▁observe ▁and ▁critique ▁the ▁process ▁ ▁May ▁be ▁able ▁to ▁dedic ate ▁greater ▁amount ▁of ▁time ▁and ▁attention ▁to ▁the ▁evaluation ▁ ▁May ▁have ▁greater ▁expert ise ▁and ▁evaluation ▁brain ▁Dis adv antages ▁ ▁May ▁be ▁more ▁cost ly ▁and ▁require ▁more ▁time ▁for ▁the ▁contract , ▁monitoring , ▁negoti ations ▁etc . ▁ ▁May ▁be ▁un famil iar ▁with ▁program ▁staff ▁and ▁create ▁anx iety ▁about ▁being ▁evaluated ▁ ▁May ▁be ▁un famil iar ▁with ▁organization ▁policies , ▁certain ▁constraints ▁affect ing ▁the ▁program . ▁ ▁Three ▁parad ig ms ▁ ▁Pos it iv ist ▁Pot ter ▁( 2 0 0 6 ) ▁ident ifies ▁and ▁describes ▁three ▁broad ▁parad ig ms ▁within ▁program ▁evaluation ▁. ▁The ▁first , ▁and ▁probably ▁most ▁common , ▁is ▁the ▁posit iv ist ▁approach , ▁in ▁which ▁evaluation ▁can ▁only ▁occur ▁where ▁there ▁are ▁" object ive ", ▁observable ▁and ▁meas urable ▁aspects ▁of ▁a ▁program , ▁requiring ▁pre domin antly ▁quant itative ▁evidence . ▁ ▁The ▁posit iv ist ▁approach ▁includes ▁evaluation ▁dimensions ▁such ▁as ▁needs ▁assess ment , ▁assess ment ▁of ▁program ▁theory , ▁assess ment ▁of ▁program ▁process , ▁impact ▁assess ment ▁and ▁efficiency ▁assess ment ▁( R os si , ▁Lip sey ▁and