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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.