There are problems in diagnosing abnormality and mental illness because the diagnosis may be based on your sex and your place in society. For example you are more likely to be considered eccentric if you are from the upper classes, higher levels of mental well-being are found in the upper classes.
The lower your social class the more you are at risk of having a mental problems. This is supported by (Cochrane and stopes roe 1980) you are also more likely to have a psychological problem if you are female. Working class house wives were found to have a high incidence of depression, some reasons for this were identified by (Brown and Harris 1978) and were thought to be the cumulative effects of the hard knocks of life that seem to effect the lower classes more than those from upper echelons of society. A more positive outlook on life as well as more positive life experiences may explain the lower incidence of problems the higher your social position.
There are also cultural problems, the Chinese are reluctant to diagnose mental illness because of the great stigma attached, In Britain someone from a different ethnic or cultural background showing symptoms the same as a white British born patient (quite normal in their ethnic culture) for example, talking to recently dead relatives, this could be misdiagnosed under the DSM 1V criteria of classifying mental illness as having a psychotic disorder (Rack 1982), And in 1977 Cochrane showed that there was an over representation of black immigrants being diagnosed with schizophrenia.
The whole problem of diagnosing psychological problems and abnormalities is shown in Rosenhans 1973 study (on being sane in insane places) in which in which he showed the problems psychiatrist's have telling the difference between those genuinely ill and those faking...