Krippendorff's alpha for predefined units — reliability

Native implementation of Krippendorff's alpha (_c_alpha) for the coding of predefined units, following Krippendorff (2019, section 12.3).

Usage

reliability_alpha(
  observations,
  method = c("nominal", "ordinal", "interval", "ratio")
)

observations: A subjects x raters (units x observers) matrix or data.frame. Rows are predefined units; columns are observers. Cells contain the value assigned by each observer to each unit (use NA for missing values).
method: One of "nominal", "ordinal", "interval", "ratio" – the metric (difference function) for delta^2_ck. See Krippendorff (2019, section 12.3.3).

A list with elements:

method: Character, e.g. "alpha_nominal".
value: Numeric – the overall alpha coefficient.
ci_lower, ci_upper: Numeric – confidence interval bounds (always NA for alpha; included for uniform output across reliability functions).
per_value: For method = "nominal": a data.frame with columns value, alpha, n giving per-category alpha (each category dichotomised against all others) and its marginal count n.c. NULL for ordered metrics.
n_observers: Number of observers (m).
n_units: Number of units with pairable values (m_u >= 2).
n_pairable: Total pairable values (n..).
coincidence: The values-by-values coincidence matrix o_ck.

Krippendorff, K. (2019). Content Analysis: An Introduction to Its Methodology (4th ed.). Sage. doi:10.4135/9781071878781