The research rm Gallup conducts many polls {or surveys) regarding the president, Congress, and political and nonpolitical issues. A commonlyr cited Gallup poll is the public approval rating til the president. For instance, the approval ratings for President Barack Obama throughout 2012 are shown in the figure. {The rating is from the poll conducted atthe end of each month.) WAN was: mm 5328!! Discuss some ways that Gallup could select a biased sample to conducta poll. How could Gallup select a sample that is unbiased