The branch Marketing Center carries out both regular researches and "according client’s order" researches. In its researches О.К.N.А. Marketing uses the actual information on the market volumes which has been collected since 2002. As is known, not all the information published in open sources is correct. Underestimating or overestimating of the market and enterprises volumes and growth rates take place everywhere. It is quite logical that it makes no sense to trust such information when development and divertissement of the company are considered. So, when collecting the information on the window market the Center thoroughly studies all the sources, compares and rechecks data contained in them. О.К.N.А. Marketing has established communications with the companies – players of the window market and has an opportunity to receive the information directly from primary source, which helps to make conclusions and forecasts on the market development.