direct ories , ▁download ▁man agers , ▁link ▁check ers , ▁proxy ▁servers , ▁web ▁filtering ▁tools , ▁har vest ers , ▁sp amb ots ▁or ▁ ▁; ▁( This ▁bad ▁b ots ▁issue ▁may ▁be ▁addressed ▁in ▁part ▁already ▁by ▁a ▁standard ▁ad ▁server ▁following ▁I AB ▁gu idel ines ▁but ▁more ▁study ▁needs ▁to ▁be ▁done ▁to ▁assess ▁whether ▁all ▁non ▁human ▁technology ▁is ▁identified ▁by ▁the ▁current ▁approaches ▁and ▁whether ▁view able ▁impression ▁technology ▁can ▁improve ▁on ▁those ▁measures . ▁ ▁Current ▁assess ments ▁suggests ▁improvement ▁with ▁view able ▁impression ▁method ology ); ▁ 4 . ▁The ▁vie wer ▁has ▁a ▁particular ▁type ▁of ▁ad ▁block er ▁installed ▁that ▁could ▁dis rupt ▁ad ▁serving ▁but ▁still ▁be ▁initi ate ▁the ▁count ▁of ▁an ▁impression . ▁ ▁( Some ▁ad ▁block ers ▁block ▁the ▁ad ▁call , ▁some ▁do ▁not . ▁ ▁More ▁study ▁should ▁be ▁done ▁in ▁this ▁area ); ▁ 5 . ▁The ▁vie wer ▁does ▁not ▁have ▁the ▁proper ▁plug - in ▁to ▁render ▁interactive ▁media ▁installed ; ▁ 6 . ▁The ▁vie wer ▁opens ▁a ▁page ▁in ▁a ▁mobile ▁device ▁that ▁is ▁not ▁configured ▁to ▁show ▁the ▁ad ▁content ; ▁ 7 . ▁The ▁vie wer ▁minim izes ▁the ▁browser ; ▁ 8 . ▁The ▁vie wer ▁opens ▁another ▁browser ▁window ▁or ▁another ▁application ; ▁ 9 . ▁The ▁vie wer ▁opens ▁another ▁browser ▁tab ; ▁ 1 0 . ▁The ▁vie wer ▁switch es ▁focus ▁to ▁another ▁browser ▁or ▁application ; ▁ 1 1 . ▁The