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                 RESEARCH LIMITATIONS

    It is important to gain an understanding of research limitations. Thinking about research limitations may foster critical thinking.  
       Every study, no matter how well it is conducted, has some limitations. 

This is why it does not seem reasonable to use the words "prove" and "disprove" with respect to research findings.  It is always possible that future research may cast doubt on the validity of any hypothesis or the conclusions from a study. 

Limitations of Case Studies

       Case studies may be viewed as having the most limitations. 
You cannot make causal conclusions from case studies. This is true because we cannot rule out alternative explanations. 
    
It is always unclear about the generality of the findings of a case study. A case study involves the behavior of one person.  The behavior of one person may not reflect the behavior of most people.  Thus, we do not know how others may behave.

Limitations of Correlational Studies

     Correlational research also has the same limitations as case studies.  Correlational research merely demonstrates that we can predict a variable from another variable.  It is demonstrating that two variables are associated.  However, two variables can be associated without there being a causal relationship between the variables. 
We cannot make causal conclusions from correlational findings because we cannot rule out all alternative explanations for correlational findings. Thus, making causal conclusions from correlational findings is a logical error.  If we find that A is associated with B, it could mean that A caused B, B caused A, or some third variable caused both A and B without there being any causal relationship between A and B.  Even if we could rule out one of the possible relationships (e.g., B caused A), we cannot rule out all alternative explanations from correlational studies.  For every correlational study, there is the possibility that some third variable caused the two variables without there being a causal relationship between the variables.
       Correlational research may also have limitations with respect to the generality of the findings.  Perhaps the study involved a specific group of people, or the relation between the variables were only investigated in some situations.  Thus, it may be uncertain whether the correlational findings may generalize to other people or situations.

Limitations of Randomized Experiments

       
Experiments involving the random assignment of participants to conditions may allow us to make causal conclusions if the variables that are manipulated are not confounded with other variables.  However, there still may be limitations with respect to the generality of the findings.  The experiment may have involved a specific group of people, certain situations, and only some of the possible conceptualizations of variables.  Thus, we may not know whether the findings will generalized to other people, situations, or conceptualizations of the variables.