The poll was conducted by American Research Group (ARG) Sample Size: 600 completed telephone interviews among a random sample of likely Republican caucus goers living in Iowa (517 Republicans and 83 no party (independent) voters). Sample Dates: September 22-27, 2011 Margin of Error: ± 4 percentage points, 95% of the time, on questions where opinion is evenly split. September 2011 Romney 21% Bachmann 15% Perry 14% Ron Paul 12% * * * * Comparison with July poll Bachmann 21% Romney 18% Paul 14% Palin 11% Gingrich 8% Perry 2% (not an official candidate at the time)