Thus, questions like "what is the meaning of life?" cannot be answered with the scientific method; there are no physically observable details related to this question, and each individual might -- and usually does -- come up with their own answer. Observation is the second step of the scientific method. In order to answer a scientific question, observations must be made that suggest possible answers to the question, or relationships with other phenomenon that might cause the questioned phenomenon. After enough observation is made, a hypothesis can be formed. This is the third and one of the most central steps in the scientific method. A hypothesis proposes a possible answer or solution to the question posed in the first step; it is an educated guess based on the observations made in the second step.

The fourth and most vital step in the scientific method is testing the hypothesis through experimentation. An experiment must be designed to control variables other than the one questioned, so that the results can be interpreted correctly. It is especially important that the experiment is not conducted from the point-of-view of trying to prove the hypothesis right, because this can lead to subjective results. In fact, some suggest that the best way to approach an experiment is with an attitude of skepticism, trying to prove the hypothesis false. Failing to do this can be interpreted not as proving the hypothesis, but leaving it a viable solution. Analyzing the results of the experiment in this way is the last step of the scientific method. A careful analysis of the observations made in the experiment can be compared to the observations made after questioning, and the hypothesis can be tested as to whether or not it matches the new information.

There are also two types of data that can be collected and analyzed via the scientific method. These are qualitative and quantitative data. Quantitative data might be thought to be more traditionally "scientific"; it involves concrete and measurable facts like frequencies and ratios. Qualitative...

Both types of data are very important in psychological research; quantitative data can support biological and neurological conclusions as well as provide information about populations at large. Qualitative data can also be useful in describing populations as a whole, and is especially useful in determining individual preference and personality (Trochim, 2006).
The scientific method and the basic differences of qualitative and quantitative data are the simple tools needed to conduct psychological research. Constructing and testing a scientific theory requires a lot of forethought, first in all aspects of the scientific method. A question must be posed in a way that is answerable through observation and analysis; a careful hypothesis must be formed and then rigorously tested in order to determine its validity, and finally it must be decided whether a qualitative or quantitative analysis will best answer the question. For some issues, the increased objectivity of quantitative data might be beneficial, but for many human problems the spectrum of response available in qualitative data might be more suitable. Regardless, conducting careful and accurate psychological research is an essential component to the science of psychology. Without this science, the practice of psychology would be non-existent. With continuing research, however, we are learning more and more about what makes us human.