Correlational, and Experimental Research Methods.

¶ … correlational, and experimental research methods. Provide clear definitions of each. Use examples that point out the factors that make each unique. Provide support for your answers.

Experimental research is perhaps most familiar to students in the form of the scientific method. The scientific method attempts to explain the cause of something and to find out why something is occurring. It creates a hypothetical explanation, or an educated guess, and tests the hypothesis under controlled conditions to determine whether and if that explanation was correct. The experiment involves independent and dependent variables. The independent variables exhibit the phenomena in question, and may be subject to circumstances that are controlled by the experimenter. The dependent variables are the effect or the result of the experiment, and are measured by the experimenter. There may also be controlled variables in the experiment, to eliminate other possible causes of the result that are not the cause of the hypothesis (Davis, 1997). A classic experiment might be to see if marigolds grow faster in sunlight than in shade. The hypothesis would be that the experimental group exposed to the sun would grow faster than the marigolds grown in the shade. The experiment would be controlled by submitting the flowers to the same kinds of fertilizers and level of water, regardless of whether they were in sun or shade.

Descriptive research, in contrast, merely describes a phenomenon. This might best be seen in the social sciences, such as anthropology, in which a particular phenomenon is simply noted and described. For example, it might be noted that populations in locations not exposed to Western media images of the female body do not manifest eating disorders like anorexia or bulimia in a statistically significant manner. Descriptive research usually does not study subjects under conditions that are created or tightly controlled by the experimenter. It does not provide the data necessary to establish with scientific validity the cause of a particular phenomena or behavior, although it can provide data that allows an experimenter to arrive at a hypothesis. It must be remembered that there are always certain difficulties with observation that makes it impossible to extrapolate causal scientific evidence, given it is difficult to observe some phenomenon and to establish strict scrutiny over some phenomena (such as comparing the effects of a particular diet under perfectly controlled circumstances for a long duration). Some descriptive observation can even be unethical, if the subjects are unaware of the fact they are being observed.

Historical research is similar to descriptive research in that it cannot, by virtue of its retrospective nature, affect the variables in question under tightly controlled conditions. A historian may examine historical or past trends in a descriptive or comparative way, and test a hypothesis by examining different types of data, like marital trends in 20th century America, for example, to see if people were marrying older or younger than in previous eras (Chapter 1: Introduction to Psychology and Research Methods, 2004, AllPsych).