Over the years, researchers have developed a multitude of methods and tools to help gather and assess data. Two of these methods involve evaluating data either quantitatively or qualitatively. Considered opposites by some, quantitative and qualitative methods of evaluation are both beneficial when you are trying to understand a certain outcome or piece of information.
Quantitative
Quantitative observations are made using scientific tools and measurements. The results can be measured or counted, and any other person trying to quantitatively assess the same situation should end up with the same results. An example of a quantitative evaluation would be "This year our company had a total of 12 clients and completed 36 different projects for a total of three projects per client."
Qualitative
More subjective than quantitative evaluation, qualitative observations are defined in science as any observation made using the five senses. Because people often reach different interpretations when using only their senses, qualitative evaluation becomes harder to reproduce with accuracy; two individuals evaluating the same thing may end up with different or conflicting results. In research and business, qualitative evaluations may involve value judgments and emotional responses. An similar example of a qualitative evaluation is "Our company created more visually compelling projects last year than this year."
Uses
Both qualitative and quantitative evaluation have their uses in a variety of fields. In science, both can be important when you are assessing experimental results or deciding what kind of hypothesis to come up with, though quantitative evaluation is sometimes more valuable to others in the field. Qualitative and quantitative evaluation can also be used to assess business performance and goal-setting. Other fields that commonly employ qualitative and quantitative evaluation methods include any of the applied sciences, psychology, anthropology and sociology.
Benefits
Both quantitative and qualitative evaluation methods have their benefits, though one is usually more appropriate than the other in any given situation. Quantitative evaluation can help remove human bias from a statistic, making it more of a reliable fact than any piece of information gathered qualitatively. Thus, accurate quantitative evaluations can be relied upon as truth. Qualitative evaluations may also entail truths, but these truths are harder to get at, and evaluators may not always agree. Still, qualitative information is invaluable precisely because it involves human interaction and interpretation. Many fields need this interpretation in order to decide how to move forward or to judge the value of past and future sources of data.