Description Usage Arguments Details Value Author(s) References Examples

Calculates the Information-Based Measure of Disagreement (IBMD) coefficient on a continuous measure.

1 | ```
IBMD(x, conf.levels = 0.95)
``` |

`x` |
n*m matrix or dataframe with n subjects and m observers. If the observer number differ for each subject missing values should be represented by the NA symbol. |

`conf.levels` |
confidence level of the interval. Must be a single number between 0 and 1. |

The IBMD was proposed (Costa-Santos, 2010) on the basis of Shannon's notion of entropy (Shannon, 1948), described as the average amount of information contained in a variable. In 2013 (Henriques, 2013) was generalized to measure the disagreement among measurements obtained by several observers, allowing different number of observations in each case. It is appropriate for ratio-scale variables with positive values and ranges from 0 (no disagreement) to 1. The confidence interval is estimated using a bootstrap procedure.

A list containing the following components:

`Subjects` |
number of subjects. |

`Observers` |
maximum number of observers. |

`IBMD` |
the information based measure of disagreement coefficient and the respective confidence interval. |

Teresa Henriques pdicss10010@med.up.pt

Costa-Santos, C, Antunes, L., Souto, A. and Bernardes, J. (2010) Assessment of disagreement: a new information-based approach. *Ann Epidemiol*, **20(7)**:555-61.

Shannon, C.E. (1948) A mathematical theory of communication. *Bell System Technical Journal*, **27**:379-423 and 623-656.

Henriques, T., Antunes, L., Bernardes, J., Matias, M., Sato, D. and Costa-Santos, C. (2013) Information-based measure of disagreement for more than two observers: a useful tool to compare the degree of observer disagreement. *BMC Medical Research Methodology*. **13(1)**:47.

Carpenter J. and Bithell J. (2000) Bootstrap confidence intervals: when, which, what? A practical guide for medical statisticians. *Stat Med*, **19(9)**:1141-1164.

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