When appraisals of a quantitative study are conducted you look to see if the measurements are valid and reliable. Reliability is the degree to which the dependability with an instrument measures an attribute (Polit & Beck, 2013). Reliability also displays an effect on accuracy and can be a measure of the studies consistency, stability and dependability. Validity refers to if the study had been conducted with sound scientific methods because bias or confounding variables may cause a compromise to the validity of a study (Melnyk & Fineout-Overholt, 2014).Applicability is when you are looking to see if the study will help you with your patients. Can you apply it to your practice and is it helpful information. Will this translate to your patient care?
I believe that together validity and reliability are the most important measures of a study with validity being the most important. They are not necessarily independent of each other. According to Polit and Beck (2013) a measuring device that is unreliable cannot be valid however it can be reliable but without validity (p.336). It is important to understand if the study is valid before you determine reliability. When looking at validity is the measurement measuring what it is supposed to measure and is it reliable. When you then you can determine if this is something that is applicable to your patient populations.
What factors must be assessed when critically appraising quantitative studies (e.g., validity, reliability, and applicability)? Which is the most important? Why?