This document also drew dispersal diagrams and regression lines for both X-rays and models. The diagrams controlling the differences between the measured values were established and the out-of-control points were counted. The upper and lower limits and repeatability coefficients were calculated. The discussion was also the subject of a standard deviations of average values assuming that the average differences are zero and were made popular in orthodontics and orthopedics of the face as Dahlberg`s error. A standard error assuming that the average differences are zero, the so-called Dahlberg error in orthodontics and orthodontics, can only be calculated for the estimation of accuracy, if the accuracy is already proven. When determining dual values, match limits and repeatability coefficients must be calculated. It is necessary to present a diagram with different measurement values and to discuss outliers. By definition, one can reproducible the agreement between successive measurement values obtained according to the same process on the same material and on the same condition (same operator, same device, same setting and same time). Reproducibility is the agreement between individual values obtained using the same method on identical test materials, but under different conditions (different operators or devices, settings or different durations). The lack of accuracy means that repeated measurements of the same value are distributed or dispersed under certain conditions.

A common convention in the field of science and technology is to implicitly express accuracy and/or accuracy through significant numbers. Unless explicitly stated, the margin of error is understood as half the value of the last important place. For example, a record of 843.6m or 843.0m or 800.0m would mean a margin of 0.05m (the last significant place being tenth place), while a record of 843m would mean a margin of error of 0.5m (the last significant figures are the units). Good agreement and proximity to predicted and experimental results and high dye adsorption capacity in a short period of time confirm the high ability of the current wastewater treatment method, while a simple separation of existing nanoparticles and good regeneration support a good applicability of Fe3O4-MNPs-AC for wastewater treatment. A control diagram to analyze double-value errors is a better statistical tool because it is used to detect excessive process variability. It aims to determine whether the extent of the dispersion of errors on double values does not exceed the expected average, i.e. an average of zero and, even given the natural statistical variability of the process, a low repeatability coefficient relative to the measurement performed.