A mixed method, according to J.Creswell (2009) combines quantitative with qualitative research. It is more than just collecting and analyzing both data, implies that the overall strength of the study is more significant than each type by itself. The described method correspond to a sequential mix method.
The researcher begins with a quantitative model (a survey) gathering information through it, and therefore uses a focus group (which is a form to apply phenomenological research). This strategy permits the researcher to put aside his own experiences or conclusions obtained through the analysis of the information retrieved from the survey and intents to understand the participant's point of view and experiences of the participants of the group under study (Creswell, 2009: p. 3-18)
References
Creswell, J. (2009). Research design: Qualitative, quantitative, and mixed methods approaches (Laureate Education, Inc., custom ed.). Thousand Oaks, CA: Sage Publications.