Evaluation of the influence of information in prevention of sexually transmittable diseases on knowledge and behaviour. several background variables / importance of God and religion in life / time spend on reading of newspapers and magazines / reading of advertisements, kind of advertisements: personal announcements, obituary notices, personal advert, advertisements of houses, rooms, cars, holidays, education, medicaments etc. / sources of information about venereal disease / attitude towards several statements about: health, responsibility for own health, influence of health advices, visits to the doctor, behaviour in favour of own health, morality of sexual relations, masturbation, homosexuality, exposure of nude on television, sexual development of children, use of contraceptives / knowledge of venereal diseases / debating of venereal diseases with partner / perceived chance to get a venereal disease / test of knowledge of venereal disease with several statements / attitude towards ( persons with ) venereal diseases and expected own behaviour if respondent would have a venereal disease / number of times respondent had a venereal disease / if having a venereal disease would respondent go to the doctor / source of knowledge about venereal diseases / actual behaviour to prevent getting a venereal disease / sexual nature / actual sexual activities / use of condoms and opinion about condoms. Background variables: basic characteristics/ residence/ household characteristics/ occupation/employment/ income/capital assets/ education/ politics/ religion/ readership, mass media, and 'cultural' exposure