LONGITUDINAL DESIGNS A. LONGITUDINAL DESIGNS ARE A SPECIAL TYPE OF...

3. Longitudinal Designs a. Longitudinal designs are a special type of systematic observation that measures variables of interest over time. b. One example of a longitudinal design is the study between happiness and longevity using the Nun Study data set conducted by David Snowdon and his colleagues. c. Even though longitudinal studies attempt to demonstrate causality, the most well conducted, excellent longitudinal studies cannot prove causation. C. Experimental Research  Researchers cannot demonstrate causation without experimental research.  In an experiment, the researcher manipulates one of the variables to see if it influences the behavior in question. If the behavior changes when one of the variables is manipulated, then the manipulated variable caused the behavior to change.  Researchers use random assignment by dividing the participants randomly into two different groups