Before just about every big movie is released, we get the tracking polls predicting how the movie will do. Going into this weekend, expectations were in the $30 million to $35 million range for “The Legend of Tarzan.” It did a little better, pulling in $38 million to come in second behind Pixar smash “Finding Dory.” 

Marketplace’s Adriene Hill looks at how tracking has changed…. and why. Click the above audio player to hear the full report.