In this section of the EBM Express course, we'll be introducing reliability and validity concepts needed to evaluate the quality of research. EBM Express is designed to build your understanding of evidence-based practice in short, manageable blocks of content.  

 

Our learning objective for this section is to define these key concepts, reliability and validity. Two of the most important critical appraisal concepts are validity and reliability.  

 

Validity is the extent to which the results of a study are true or how close the results are to fact. This is often represented by multiple arrows shot at a target with the bullseye representing truth. The closer your arrow is to the bullseye, the more valid your results would be.  

 

Studies can also be thought of as having both internal and external validity. Internal validity is the extent to which the experiment demonstrated a cause effect relationship between the independent and dependent variables. External validity is the extent to which one may safely generalize from the sample studied to the defined target population and to other populations.  

 

Reliability is the extent to which the results of the experiment are replicable. In other words, could you repeat the research with similar results? The research methodology of the study should be described in detail so that the experiment could be repeated with similar results. This is often represented as a target with multiple arrows each striking the same spot. There are several tools and measures that aim to determine the validity and reliability of a study. The appropriate tool can vary depending on the type of study conducted.  

 

Tools and measures used in appraising specific types of studies will be introduced in other sections of EBM Express. In summary, validity is the extent that a study's results are true or factual. Reliability is the extent that a study's results can be replicated with the same results. Several tools attempt to measure a study's validity and reliability, and the right tool to use can vary based on the type of study.