Czechs ranked Roma worst in a survey of their opinions on certain nations and ethnic groups, conducted by the Institute of Sociology of the Czech Academy of Sciences. Over 75 percent of respondents consider Roma immoral, 85 percent said they were lazy, and over four-fifths believe they violate laws. But Czechs consider Muslims the most violent. According to the authors, these opinions are based on the belief of many Czechs in the congenital lower intelligence of some ethnic groups and nations, and the superiority of others - 70 percent are convinced of this.