Until recently it was difficult to obtain funding for research that was based on qualitative methods, because there was the erroneous belief they could not make any useful contribution to science. This R.S. Peters excerpt explains very well the importance of these methods.
"The main function of the measurements in science is surely to facilitate the test of the hypothesis by expressing them in more exact form. The quantitative techniques allow science people to respond in more precise form to the problems posed by less refined qualitative methods. But it little matters to do measurements, unless the goal of those techniques is the test of fertile hypothesis. Measurement by itself does not produce fertile hypothesis, laboratories or research subsidies either. In physical sciences, an enormous amount of qualitative analysis, not only precedes to the use of quantitative techniques, but it also provides postulares about the physical world, which are incorporated to the measurement techniques. The qualitative experiences of daily life provided Galileo the necessary foundation to undertake the quantitative study of a big variety of problems. The contribution to the progress of psychological theory by men like Freud and McDougall, who did not worry about premature attempts of measurement, was more substantial than the one of those who were obsessed by the need to collect quantifiable data. Science progress depends as much of the development of fictitious postulates as of the exact techniques to prove them. To embark in this last one, without having developed the previous thing, would be like buying a harvester to use it in the North Pole." (p.402)
Free translation from:
G.S. Brett, Historia de la Psicologìa
Editorial Paidòs, Buenos Aires
Edited and abridged by R.S. Peters