<p>To measure the power, they used:</p>
<p>$ earnings over the past year
media presence
and other small things such as how many people follow them on twitter.</p>
<p>the reasons britney spears made the list:</p>
<p>britney spears is number 1 followed person on twitter, number 4 searched on google, number 5 searched on yahoo, and number 1 searched on bing. she had a tour that was the 5th highest grossing tour of all time in 2009 and was the only artist to have a song open at number 1 on the billboard top 200 list for her single “3”</p>