Evaluation, whether it be in psychology, education, or medicine, is an attempt to better understand what is going on in a certain place at a certain time. We might, for instance, wonder if a certain teaching strategy is more effective than another for the students in a classroom. Alternatively, we might wonder how useful a certain drug is at combating an illness. Both scientific and humanistic approaches to evaluation can help us do this, but they do so in different ways.
Scientific approaches to evaluation rely on the scientific method and are typically most concerned with numbers. These approaches are often considered to be more objective. For true scientific evaluation, individuals are randomly assigned to a control or experimental group. Consider the case of a new drug designed to combat a disease. It would be possible to take 100 people, give 50 of them the new drug (the experimental group), and give 50 of them a previously existing drug (the control group). At the end of a week, scientists could then evaluate their symptoms or test for the presence of the disease and compare the two groups. They would look at the number of patients cured across the two groups and then decide if the new drug was more effective than the old. The same kind of procedure might occur within a classroom, but instead of looking at the number of diseases patients had, researchers would look at student test scores. Based on a new curriculum, for instance, did students score better on a test? The numbers can tell us if a new teaching strategy is more or less effective.
However, these numbers only tell one part of the story. Humanistic evaluation looks more deeply at people's experiences during a given time. These evaluations tend to be qualitative, looking at the ways that people describe their experiences, and instead of "objective" tests, humanistic evaluation relies on descriptions and interviews. Suppose we take the example above of test scores, and we realize that at a school, most students scored better on a test with a new teaching method but nothing changed for Black or Hispanic students. Numbers do not tell us how or why nothing has changed. Using interviews, we might find out that the new curriculum favors white populations and fails to address diverse points of view. Alternatively, we might find that certain teachers are not effective at teaching the new curriculum for any number of reasons.
In short, scientific approaches to evaluation give us generalizations about the number of people affected and to what degree, while humanistic approaches tell us about people's experiences and why something is the case. Occasionally, these approaches come together (called mixed methods) and attempt to give us an even fuller view of what is happening.