Brain tumor . Depending on where it is, it can cause different types of hallucinations. If it's in an area that has to do with vision, you may see things that aren't real. You might also see spots or shapes of light. Tumors in some parts of the brain can cause hallucinations of smell and taste.
One of the key factors in this process is the identification and operational definition of variables -- traits, characteristics, or other measurable factors that can have different values -- that impact the phenomenon of interest. One is primarily interested in two types of variables: independent variables and dependent variables. The independent variable is the variable that is being manipulated by the researcher. For example, Dr. Harvey has a theory that the way that people dress affects how they are treated by others in the workplace.
In experimental studies, where the independent variables are imposed and manipulated, the dependent variable is the variable thought to be changed or influenced by the independent variable. Example: study title: Effects of a new tooth paste (YummyTooth) on incidence of caries in 1st grade children. is the independent variable and Y is the dependent variable-the outcome, and Z is the type of subjects represented. A simple example would be: The effects of tomatoes on risk of prostate cancer in Scandinavian men.