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Table 2 Statistical data of the intra- and interobserver reliabilities of the different histological criteria

From: Development and reliability of the histological THROMBEX-classification rule for thrombotic emboli of acute ischemic stroke patients

Intra- and interobserver reliability
Rater (N) Few Moderate Many
Number of platelets: κ [95% CI]
 R1 (14)  0.12 [ 0.31 to 0.07] 0.39 [ 0.08 to 0.87] 0.58 [0.051.00]
 R2 (21) 0.7 [0.311.00] 0.52 [0.160.87] 0.7 [0.41.00]
 R1–R2 (130) 0.51 [0.320.7] 0.23 [0.10–0.36] 0.19 [0.04–0.34]
Rater (N) Stratus Cirrus Cumulus
Distribution of platelets: α [mean diff.; limit: lower–upper]
 R1 (14) 0.89 [0.19; − 0.18 to 0.55] 0.56 [ 0.19;  0.75 to 0.36] 0.79 [0.01; − 0.44 to 0.46]
 R2 (22) 0.87 [− 0.02; − 0.46 to 0.42] 0.81 [0.06; − 0.41 to 0.53] 0.84 [− 0.04; − 0.47 to 0.39]
 R1–R2 (127) 0.62 [− 0.07; − 0.69 to 0.55] 0.56 [ 0.01;  0.59 to 0.56] 0.62 [0.08; − 0.52 to 0.68]
Rater (N) Fine Coarse Dense
Property of fibrin net: α [mean diff.; limit: lower–upper]
 R1 (14) 0.91 [0.01; − 0.25 to 0.27] 0.80 [− 0.01; − 0.33 to 0.30] 0.92 [0.01; − 0.28 to 0.30]
 R2 (23) 0.66 [− 0.14; − 0.59 to 0.31] 0.57 [0.15;  0.35–0.65] 0.73 [− 0.01; − 0.50 to 0.47]
 R1–R2 (131) 0.73 [0.07; − 0.36 to 0.51] 0.45 [ 0.01;  0.49 to 0.47] 0.8 [− 0.07; − 0.46 to 0.33]
Rater (N) Few Moderate Many
Number of neutrophil granulocytes: κ [95% CI]
 R1 (14) 0.66 [0.251.00] 0.29 [ 0.21–0.78] 0.43 [ 0.10–0.96]
 R2 (23) 0.38 [0.03–0.72] 0.47 [0.13–0.81] 0.64 [0.271.00]
 R1–R2 (132) 0.38 [0.20–0.56] 0.22 [0.06–0.39] 0.35 [0.18–0.52]
Number of intact neutrophil granulocytes: α [mean diff.; limit: lower–upper]
 R1 (14) 0.71 [0.03; − 0.28 to 0.34]
 R2 (23) 0.43 [0.02; − 0.65 to 0.68]
 R1–R2 (132) 0.65 [− 0.03; − 0.47 to 0.41]
Number of intact red cells: α [mean diff.; limit: lower–upper]
 R1 (14) 0.94 [0; − 0.23 to 0.22]
 R2 (23) 1.00 [0; − 0.04 to 0.04]
 R1–R2 (132) 0.64 [0.06; − 0.48 to 0.60]
  1. R1, intraobserver reliability for rater I; R2, intraobserver reliability for rater II; R1-R2, interobserver reliability. The related number of cases is indicated in parentheses. Weighted Cohen’s kappa (κ) was calculated for categorically scaled criteria. CI = confidence interval. For the continuously scaled criteria, Cronbach’s alpha is used. The related Bland–Altman plots can be seen in the Additional file 1: Figs. S1, S2, S3. Numerical values indicating sufficient reliability are written in italics. Chosen tolerance levels: κ = 0.5; α = 0.6.
  2. κ < 0 = poor, 0 ≤ κ ≤ 0.2 = slight, 0.2 < κ ≤ 0.4 = fair, 0.4 < κ ≤ 0.6 = moderate, 0.6 < κ ≤ 0.8 = substantial, and 0.8 < κ ≤ 1 = (almost) perfect agreement.
  3. α < 0.5 = unacceptable, 0.5 ≤ α < 0.6 = poor, 0.6 ≤ α < 0.7 = questionable, 0.7 ≤ α < 0.8 = acceptable, 0.8 ≤ α < 0.9 = good, and 0.9 ≤ α = excellent.