Prejudice and bias are described as an embarrassing phenomenon of research work in social sciences. They concern both quantitative and qualitative research. Authors working in both antagonistic paradigms such as positivist, post-positivist and constructivism, interpretivism generally point to the main patterns showing the aspects of bias. They usually indicate the bias in the process of the research design, among the subjects involved in the study or including the reliability and quality issues of the study. Gender is also mentioned as not neutral and as factor raising bias. In this review and methodological article the concept of bias is narrowed down to discussing these that concern chosen elements of research design process and the three actors involved as researcher, gate-keeper and censor. The gender issue bias, detailed analysis of design process bias, as well as quality of research bias and informant bias are briefly mentioned in the article but are extensive enough to be discussed in a separate paper.