"Several polls in the run-up to the referendum showed Chavez to be the likely winner; the most recent ( 4–8 August) and comprehensive was the poll by Evans/McDonough Company, Inc., with Varianzas Opinion. With a nationwide sample of 2000 and a margin of error of 2.2 percent, it showed Chavez ahead by 50 to 38 percentage points among registered voters (up from 49–41 in July).""Polling and the Ballot: The Venezuelan Referendum"CEPR: Center for Economic and Policy Research. Accessed 30 June 2006]
Maria M. Febres Cordero and Bernardo Márquez (2006), "A Statistical Approach to Assess Referendum Results: the Venezuelan Recall Referendum 2004", International Statistical Review, 74(3); abstractArchived 7 June 2011 at the Wayback Machine
Maria M. Febres Cordero and Bernardo Márquez (2006), "A Statistical Approach to Assess Referendum Results: the Venezuelan Recall Referendum 2004", International Statistical Review, 74(3); abstractArchived 7 June 2011 at the Wayback Machine