Representatives of some OPEC and non-OPEC nations will meet in Abu Dhabi on Aug. 7-8 to discuss why some of them are falling behind in their pledges to cut production, according to an OPEC statement.  The meeting, co-chaired by Kuwait and Russia, will examine reasons why some countries aren’t fully implementing their cuts, it said. Some nations will argue that the independent sources used by OPEC to assess compliance overestimate their production, according to two people familiar with the matter, who asked not to be identified because the discussions aren’t public.  Targets for output reduction are based on production estimates from six independent parties, known as “secondary sources.” Last year, as the deal was being negotiated, Iraq complained about these estimates, claiming they aren’t accurate. Other members of the Organization of Petroleum Exporting Countries are also putting the blame on secondary sources for their poor performance, said two people.