Agreement Between Two Groups
Methods of assessing conformity between observers depending on the nature of the variables measured and the number of observers It is important to note that, in each of the three situations in Table 1, the percentages of success are the same for both examiners, and if both examiners are compared to a usual test of 2 × 2 for the associated data (McNemar test); there would be no difference between their benefits; on the other hand, agreement among observers varies considerably from country to country in all three situations. The fundamental approach is that "convergence" quantifies the concordance between the two examiners for each of the "pairs" of marks and not the similarity of the overall pass percentage between the examiners. Consider a situation in which we would like to evaluate the adequacy between hemoglobin measurements (in g/dl) with a hemoglobinometer on the hospital bed and the formal photometric laboratory technique in ten people [Table 3]. The Bland Altman diagram for this data shows the difference between the two methods for each person [Figure 1]. The mean difference between the values is 1.07 g/dl (with a standard deviation of 0.36 g/dL) and the 95% match limits are 0.35 to 1.79. This means that the hemoglobin level measured by a given person`s photometry can vary from 0.35 g/dl greater than 1.79 g/dl measured by photometry (this is the case for 95% of people; for 5% of individuals, variations could be outside these limits). This obviously means that the two techniques cannot be used as substitutes. It is important that there is no single criterion for acceptable compliance limits; This is a clinical decision that depends on the variables to be measured. An agreement between two persons or groups involved in a war, struggle or disagreement to stop it for a certain period of time Vanbelle, S., & Albert, A. (2009). Agreement between an individual evaluator and a group of evaluators. Statistica Neerlandica, 63, 82-100th formal agreement, often an agreement that secretly hits people Statistics κ can take values from − 1 to 1 and are arbitrarily interpreted as follows: 0 = concordance equivalent to chance; 0.10-0.20 = light match; 0.21-0.40 = fair agreement; 0.41-0.60 = moderate concordance; 0.61-0.80 = essential correspondence; 0.81-0.99 = almost perfect match; and 1.00 = full compliance. Negative values indicate that the agreement respected is worse than what is expected by chance.
Another interpretation is that Kappa values below 0.60 indicate a significant degree of disagreement. Hollander, M., &Sethuraman, J. (1978). Examination of concordance between two groups of judges. Biometrics, 65, 403-411. It is often interesting to know whether measurements made by two (sometimes more than two) different observers or by two different techniques give similar results. This is called concordance or concordance or reproducibility between measurements. Such an analysis considers the pairs of measurements, either categorical or both numerically, each pair having been made on an individual (or a pathology slide or an X-ray). Cohens Kappa (κ) calculates the Inter Observer correspondence taking into account the expected agreement as follows: Cohen, J. . . .