The qualitative vs. quantitative debate lies at the heart of the differences between anthropology and sociology.
Quantitative assumes an objective observer that is gathering empirical evidence that explains an objective reality. Quantitative analysis wants to break down the phenomenon into discrete units that can be turned into numbers that can be processed through the methods of statistics and represented in a variety of graphical interfaces. The advantages of this type of analysis is that it can allow for novel understandings of the "whole" by seeing which elements are outliers and which elements are common cases. Quantitative analysis strives to replicate the objectivity of the hard sciences, and is more often found in Sociology and the social sciences.
Qualitative analysis tends to avoid the methods of statistics in favor of case studies and participant observation, and is more often found in the humanities and Anthropology. Qualitative analysis is less concerned with turning their object of study into data points that can be turned into graphical representations and statistics. Instead of drawing from the ideal of scientific objectivity, they favor an interpretive approach that takes it as a given that many factors cannot be accurately quantified but still play a key role in how a given phenomenon work.
These two approaches are far from mutually exclusive, and almost every study has elements of both types of analysis. Cyborg anthropology traditionally focuses on the more qualitative aspects, but can approach very precise quantitative methods through the use of algorithms and computer software. danah boyd's social graphic Facebook application is one example of an anthropologist partnering with a technologist to create scalable methods for social analysis.