Each row $of$ data $in$ the sheet named $DoubleClick$ contains information related $to$ a specific keyword

for a particular search engine. $In$ order $to$ compare the campaign performance $of$ different search

engines, $we$ first need $to$ decide the metrics $on$ which $we$ want $to$ compare performance. For example, $if$

$we$ choose revenue $as$ such a metric, then $we$ can say that the search engine which generates a higher

revenue has a better performance than another search engine that generates lower revenue. $We$ refer

$to$ such metrics $as$ KPIs $(Key$ performance Indicators$).$ Which $of$ the variables $(column$ names$)$ already

included $in$ the data sheet can serve $as$ these KPIs?

Your response should $beinno$ more than half a page.