the extent to which the outcomes of a study result from the variables that were actually manipulated, measured, or selected in the study rather than from other variables not systematically treated (Shavelson, 1996).
How representative of the population under investigation is the sample chosen, is the researcher representing the views of those studied
The ability to show that the independent variable was responsible for the change in the dependent variable because the researcher was able to control all the variables.
The extent to which the causes of an effect are established by an inquiry.
A measure of how well a study accounts for and controls all the other differences (that are not related to the study question) among the people being studied. An internally valid study usually requires a “control group” and “random assignment.” In an experiment, this kind of validity means the degree to which changes that are seen in a “dependent variable” can be linked to changes in the “independent variable.
The degree to which a study is logically sound and free of confounding variables.
factors within a study design that may have influenced the findings.
The extent to which a study evaluates the intended hypotheses.
The approximate truth about inferences regarding cause-effect or causal relationships. Thus, internal validity is only relevant in studies that try to establish a causal relationship. It's not relevant in most observational or descriptive studies, for instance. But for studies that assess the effects of social programs or interventions, internal validity is perhaps the primary consideration. In those contexts, you would like to be able to conclude that your program or treatment made a difference -- it improved test scores or reduced symptomology. But there may be lots of reasons, other than your program, why test scores may improve or symptoms may reduce. The key question in internal validity is whether observed changes can be attributed to your program or intervention (i.e., the cause) and not to other possible causes (sometimes described as "alternative explanations" for the outcome).
In a study, internal validity refers to the ability of the researcher to attribute differences in the groups or participants to the independent variable.
the extent to which the findings of a study accurately represent the causal relationship between an intervention and an outcome in the particular circumstances of that study. The internal validity of a trial can be suspect when certain types of biases in the design or conduct of a trial could have affected outcomes, thereby obscuring the true direction, magnitude, or certainty of the treatment effect.
the extent to which the results of a study (usually an experiment) can be attributed to the treatments rather than a flaw in the research design; in other words, the degree to which one can draw valid conclusions about the causal effects of one variable on another.
the extent to which an observed effect can be attributed to an intervention, rather than to flaws in the research design; the degree to which researchers can draw valid conclusions about what caused changes in the variables. See: external validity, variable.
The degree to which there can be reasonable certainty that the independent variables in an experiment caused the effects obtained on the dependent variables.
(1) The rigor with which the study was conducted (e.g., the study's design, the care taken to conduct measurements, and decisions concerning what was and wasn't measured) and (2) the extent to which the designers of a study have taken into account alternative explanations for any causal relationships they explore (Huitt, 1998). In studies that do not explore causal relationships, only the first of these definitions should be considered when assessing internal validity. See also validity.
(see also external validity, treatment effect) A trial has internal validity if, apart from possible sampling error, the measured difference in outcomes can be attributed only to the different therapies assigned.
The degree to which a study is successful at measuring what it purports to measure, with all confounds removed and the dependent variable sensibly measured.
The extent to which the design and conduct of the trial eliminate the possibility of bias.
The confidence one can have in one's conclusions about what the intervention actually did accomplish. A threat to internal validity is an objection that the evaluation design allows the causal link between the intervention and the observed effects to remain uncertain. It may be thought of as a question of the following nature: could not something else besides the intervention account for the difference between the situation after the intervention and the counterfactual? See also counterfactual situation, evaluation design, external validity, intervention, intervention logic, selection bias.
See validity.(empty)(empty)
Internal validity is a form of experimental validity Mitchell, M. and Jolley, J. (2001). Research Design Explained (4th Ed) New York:Harcourt.. An experiment is said to possess internal validity if it properly demonstrates a causal relation between two variables Brewer, M. (2000).