Qualitative inquiry is concerned with rich, narrative description of events in a natural or spontaneous setting, in direct contrast to quantitative research's quest for cold, hard numbers to classify phenomena occurring in strictly controlled clinical labs. Qualitative investigators want to understand as much as they can about their study focus from the subject's point of view; it's all about wordy depth. Quantitative researchers, on the other hand, care more about ranges of possible factors influencing each other in a linear fashion; for them, neatly categorized numerical breadth is what matters.
Qualitative researchers welcome, or at least manage, bias. They acknowledge the subjectivity they -- and all human researchers -- inherently bring to their studies. They seek to be up close and personal with their human subjects, called informants, data and their interpretation. Quantitative investigators, however, maintain that objectivity is both possible and necessary to conduct well-designed, intellectually rigorous research, and try to be clinically cool, detached experts.
At the beginning of a project, qualitative investigators operate on an initial hunch of what they might see. Research design emerges or unfolds amid actual observation in particular study setting. In quantitative design, the researcher concretely knows what he's looking for, and seeks to be predictive based on outside sources such as literature reviews. During data collection in qualitative inquiry, researcher, informant and data all reciprocally influence one another at the same time, making it virtually impossible to determine clear origins and results of phenomena.
Quantitative research aims to identify observable causes before or alongside quantified effects presented in statistical form. Qualitative researchers don't care whether the chicken or the egg came first, how many eggs were laid and the number of tries it took -- they care only about how the chicken hatched and crossed the road. Analyzing data in qualitative research occurs on a continuous basis starting from observation phase, but in quantitative inquiry, analysis follows data collection.
In qualitative research, phenomena can only be understood from perspective and circumstances of a particular time period; in quantitative inquiry, broad and non-contextual generalizations of clinical observations prevail. Because qualitative data comes from more natural, idiosyncratic environments, generalization usually cannot happen, which is fine in qualitative research.