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.
Dependent and Independent Variables. The key to designing any experiment is to look at what research variables could affect the outcome. There are many types of variable but the most important, for the vast majority of research methods, are the independent and dependent variables. A researcher must determine which variable needs to be manipulated to generate quantifiable results. The independent variable is the core of the experiment and is isolated and manipulated by the researcher. The dependent variable is the measurable outcome of this manipulation, the results of the experimental design.