The United Nations Office on Drugs and Crime (UNODC) has not yet released the full Afghanistan Opium Survey for 2007 which will contain details of the methodology used. However, we believe this year's opium survey used similar methodology to that used in the 2006 survey. This is described in detail in the 2006 Opium Survey available at:
http://www.unodc.org/pdf/research/AFG05%20_full_web_2006.pdf.
The UNODC calculated opium poppy cultivation by use of a sampling approach that combined interpretation of satellite imagery with field surveys on the ground. In order to estimate opium yield per hectare, the UNODC measured both the size of opium capsules and the density of cultivation.
The 2006 Opium Survey stated that the extent of heroin production is more difficult to establish, as opium in Afghanistan is primarily exported to foreign markets, where it is subsequently processed into heroin. Additionally, heroin laboratories, by their nature, are clandestine.