This chapter identifies some possible sources of systematic error prior to its start with regard to the nature of the participants and the research setting. The schizophrenic patients had more previous marriages, yet had been together for a much shorter period than the depressed patients. It is partly due to the fact that the schizophrenic patients had the current marriage started at an older age, and partly to the fact that some of them had re-established a new confiding relationship after previous break-up. More than one-fourth of the spouses (predominantly men) of the schizophrenic patients and 8% of the depressed patients indicated that they were also psychiatric sufferers. Although some studies suggested a relationship between smoking and a specific personality dimension and anxiety control in the normal population, there is no information available in this study to ascertain if the same might be true to our patient groups.