Well, according to Alan Bryman in his research article Integrating quantitative and qualitative research: how is it done?, this is a theme that is still open to debate. He uses these 5 questions in separating qualitative, quantitative and mixed-methods approaches:
- Are the quantitative and qualitative data collected simultaneously or sequentially? (Morgan, 1998; Morse, 1991).
- Which has priority – the quantitative or the qualitative data? (Morgan, 1998; Morse, 1991).
- What is the function of the integration – for example, triangulation, explanation, or exploration? (Creswell, 2003; Creswell
et al., 2003; Greene et al., 1989).
- At what stage(s) in the research process does multi-strategy research occur? (Tashakkori and Teddlie, 1998). It may be at stages of
research question formulation, data collection, data analysis, or data
interpret- ation.
- Is there more than one data strand? (Tashakkori and Teddlie, 2003). With a multi-strand study, there is more than one research method and
hence source of data. With a mono-strand study, there is one research
method and hence one source of data. However, whether a mono-strand
study can genuinely be regarded as a form of mixing methods is
debatable.
In regards to your question, I would say that if by "criteria" you mean forming hypotheses that you later test with quantitative methods, that would clearly be a mixed-methods approach. If not, you are probably more in a grey area.