Krippendorff's alpha showed a slight agreement with α = 0.15.
On average, science and engineering students reported only slight agreement with the statement, "I'm upbeat about my post-graduate career prospects".
Kappa values as follows were interpreted as: < 0: less than chance agreement, 0.01 - 0.20: slight agreement, 0.21 - 0.40: fair agreement, 0.41 - 0.60: moderate agreement, 0.61 - 0.80: substantial agreement and 0.81 - –0.99: almost perfect agreement [26,27].
Agreement rating: κ = 0 no agreement; 0.01 to 0.2 slight agreement; 0.21 to 0.40 fair agreement; 0.41 to 0.60 moderate agreement; 0.61 to 0.80 good agreement; and 0.81 to 1 excellent agreement.
A commonly used scale designates a k value of 0.01 0.20 as slight agreement, 0.21 0.40 as fair agreement, 0.41 0.60 as moderate agreement, 0.61 0.80 as substantial agreement, and 0.81 0.99 as almost perfect agreement [20].
Agreement was categorized a priori as follows: k of 0.61 or greater was considered substantial agreement; k of 0.21 to 0.60, moderate agreement; and k of 0.20 or less was considered slight agreement.
There was only a slight agreement between interview and diary reports of having headaches on at least 50%% of days and one or more headache disorders (Kappa 0.14, 95%% CI: 0.05 0.23; Table 3).
Inter-rater and intra-rater agreement was analysed with the interclass correlation coefficient (ICC) (two-way mixed model, type absolute agreement), taking into consideration that an ICC of 0 0.2 represents slight agreement, 0.21 0.4 fair agreement, 0.41 0.6 moderate agreement, 0.61 0.8 substantial agreement and 0.81 1 excellent agreement [21].
According to Landis and Koch this should be interpreted as "slight agreement".
According to this scale the interpretation of Kappa coefficients is as follows: <0 = Less than chance agreement, 0.01 0.2 = Slight agreement, 0.21 0.40 = Fair agreement, 0.41 0.60 = Moderate agreement, 0.61 0.8 = Substantial agreement, 0.81 0.99 = Almost perfect agreement [63].
