Data about personal networks (called also egocentered networks) and their characteristics are increasingly used in social science research, especially in research about the quality of life, social support and similar. Since all data about a person's social network are usually obtained from the respondent himself, the quality (reliability and validity) of such measurements is a very important issue. In this paper the results of a recent study on the quality of measurement of personal network measures are presented. The data were collected in the year 2000 by computer assisted face-to-face and telephone interviews on a random sample of 1033 residents of Ljubljana. One ofthe more important effects that has not been studied yet, is the effect of data collection technique - "by alters" or "by questions". After we obtain the list of alters with name generators, we can ask name interpreter questions in two ways. One way (by alters) is to take each alter individually and to ask all questions about him/her, going alter by alter until the end of the list of alters. The other way (by questions) is to take the question and ask this question for all alters on the list, going question by question until the end of the list of name interpreter questions. Among other things the results have shown that data of the best quality are obtained by telephone/by alters data collection method. Therefore, that method was used in the study on social support networks of Slovenians as social capital in 2002.