Within the Campaigns tab of your account, you will be able to see detailed performance data for each of your ad groups, including average position, number of impressions, click-through rate, number of clicks, average cost-per-click, number of conversions, cost-per-acquisition, total revenue, return-on-ad-spend and total spend. Using this information, you will be able to compare performance between different ad groups, as well as within an ad group during testing, and make the necessary changes to improve their performance.