Dear Editor,

I was interested to read the paper by Rostaminia and colleagues published in December 2013 [1]. The authors aimed to assess the interrater agreement/reliability of 3D endovaginal ultrasound for scoring levator ani deficiency (LAD). As the authors pointed out, all correlation coefficients at individual sites as well as overall scores were positive at >0.63 and significant at <0.0001 [1]. My question is why the authors did not use the well-known intraclass correlation coefficient (ICC), agreement type and not consistency, or weighted kappa in case of qualitative variables to assess reliability [2–5]. As the authors pointed out in their conclusion, 3D endovaginal ultrasound for assessing levator ani muscle deficiency had excellent agreement between raters. Clinically, 0.6 correlation coefficient means moderate and not excellent reliability; moreover, statistically significant results have nothing to do with the clinical importance of the findings. The authors also concluded that this level of concordance supports the validity of 3D endovaginal ultrasound technique and scoring method. It is important to mention that reliability (precision) and validity (accuracy) are two completely different methodological issues being assess by different statistical tests and should not be confused with each other [2–5]. Therefore, such misinterpretations and misconceptions should really be avoided by clinicians; otherwise, we will face patient mismanagement in our routine clinical practices [3–5].