Differences between qualitative research and quantitative research:
Purpose: To understand & interpret social interactions (Qual) To test hypotheses, look at cause & effect, & make predictions (Quan)
Sample selection: Smaller & not randomly selected (Qual) Larger & randomly selected (Quan)
Scientific Method: Exploratory or bottom-up: researcher generates a new hypothesis and theory from the data collected (Qual) Confirmatory or top-down: the researcher tests the hypothesis and theory with the data (Quan)
Results: Particular or specialized findings that is less generalizable (Qual) Generalizable findings that can be applied to other populations.
More details can be found in here.
I think these two methods are both solid way of doing research. They both have their merits and limitations. Sometimes the choice comes down to the resources that you have and your research intention. If I don’t have a the ability to recruit more than 10 people to participate, quantitative research is obviously not the optimal choice to my situation. And if I want to prove the assumption that college students prefer pepsi over coke, qualitative research can’t be a reliable resources for that. And if I want to find out what’s favorite choice of beverage for college students and why they like it, the two can play together seamlessly.