Reliability and validity in medical research

Scientists commonly refer to study instruments duringmedical research. In fact, the reliability and validity issuesgo beyond psychometric studies and can be linked withany kind measurements. In this study we aimed to explainthe reliability and validity concepts by giving examples.It is possible to evaluate the reliability and validity of aninstrument by scientific methods. If we speak of reliability,we have to mention stability (having the same results inrepeated measurements from the same sample), equivalence,and homogeneity. Homogeneity is related withinternal consistency; it measures how close results areobtained from items intending to measure the same structure.In other words, how consistent are the different itemsin measuring the same feature? Accordingly, the followingtypes of reliability can be measured: parallel forms, test/retest, inter-observer reliability, split half, and Cronbachalfa. From the point of validity, we will discuss contentvalidity, predictive validity, construct validity, concurrentvalidity, and face validity. Science means measurement.Wrong measurements will make our evidence and thusthe treatments unreliable. Therefore, medical researchershave to give utmost importance in receiving valid and reliableresults from the instruments they use.