Critical Appraisal of Evidence
Critical appraisal plays a significant role in the application of evidence-based practice by advanced practice nurses. The process involves systematic identification of a study’s strengths and weaknesses and assessment of the usefulness of results (Heydari & Hajiabadi, 2016). Many factors are important in the critical appraisal of quantitative studies. Reliability and validity are some of the factors that a nurse should consider in critical appraisal. Validity is the degree to which an instrument measures a quantitative concept (Heale & Twycross, 2015). Validity emerges in two types, including “construct” or “internal” validity, and “external” validity. The first category of validity is the extent to which a study uses valid methods and measurements, which enables legitimate inference about the results. External validity relates to the potential to generalize findings depending on the methodology used. Reliability refers to the extent to which an instrument is consistent, indicating that an instrument should provide responses that are approximately the same after a test is repeated (Heale & Twycross, 2015). Therefore, studies differ in quality in terms of the two factors.
Although both validity and reliability are essential factors in the critical appraisal process, validity is the most important. Both internal and external validity are vital because they involve the analysis of meaningfulness, appropriateness, and significance of a study (Heydari & Hajiabadi, 2016). The validity of a study suggests that the researcher can verify the findings to match the study that was performed. For example, a valid instrument allows the accuracy of the findings and reflects what a researcher measures or evaluates. The quality is vital to avoid misleading findings. Besides, through external validity, the results of a quantitative study can be generalized to other advanced nursing settings. Therefore, the aspect is critical to ensure that a quantitative study is relevant and useful to the researcher and nurses in practice.
