The intra-observer agreement is fully visualized with the Bland-Altman agreements, which in turn can be directly linked to VCA-derived RCs. Integrating several sources of potential variation into the data (for example. B using different observers) leads to expanded models from which appropriate RCs can be deducted for evaluation of the agreement. It is difficult to indicate the sample sizes required for these linear models of mixed effects, but as a general rule, 20 observations per continuous variable and factor level of the category variable should be included in the statistical model. The data from Study 1 were presented graphically by the Bland-Altman plots with corresponding matching limits, which are defined by the estimated average difference between the measurement values – 1.96 times the standard deviation of differences between the measured values. These plots were supplemented by lines resulting from linear regressions of differences on averages, also known as Bradley Blackwood processes  to support the visual assessment of trends on the scale. Data from Study 2 were presented by observers over time using line diagrams. Taylor, D.R. A useful method for calculating Harris and Lahey`s weighted agreement formula. Behavioural Therapist 1980,3, 3. In summary, we described three commonly used measurement error message methods, all derived from the identical data set. Regardless of one of the three methods used, the report should indicate the measurement and include both the average value and the standard deviation of the measurement, expressed both in actual units of measurement and after standardization.
Data must be presented independently for inter-and-intraobserver variability. The final report should therefore contain 8 digits for each of the variables whose variability is tested. These figures are: average and standard deviation (2) for both intraobserver and interobserver variability (×2), expressed in both actual units of measurement and percentages (×2), resulting in 2××.2-2-8 digits. Zaki R, Bulgiba A, Ismail R, Ismail NA. Statistical methods of measuring compliance with medical devices measuring variables continuously in comparative studies of methods: a systematic verification. PLoS ONE. 2012;7 (5):e37908. In Study 1, 30 patients underwent a pre-operative examination to assess ovarian cancer and their scans were examined twice by the same observer to verify the observer`s consistency. In Study 2, 14 patients with glioma were scanned up to 5 times.
The results were reviewed by three observers to review the agreement between the observers. The outcome variables were SUVmax in Study 1 and Total Cerebral Hemispheric Glycolysis (GES) in Study 2. Repeatability in relation to reproducibility: reproducibility establishes the proximity of the match between the measurements at the same condition, i.e. with the same laboratory, with the same observer and the same equipment (scanner PET, image reconstruction software), at short intervals. Reproducibility is about the proximity of the agreement between actions under all possible conditions for identical themes, i.e. using different laboratories, observers or PET scanners or assessing daily variation. Fleiss, J. L. Measure of nominal scale agreement among many advisors. Psychological Bulletin 1971,76, 378-382. According to the VCA, patient and remains variance was estimated at 47.53 and 0.787, respectively, reflecting the variance between patients to be the dominant source of variation in the data.