Chart error

Position errors in the chart caused by inaccuracies in surveying and by errors in the reference geodetic system.

- Circular error probable (CEP). The radius of a circle, centred on the measured position, inside which the true position lies with 50% confidence.

- Confidence interval. The numerical range within which an unknown is estimated to be with a given confidence.

- Confidence level. The percentage of confidence that a given statement is correct, or the percentage of confidence that a stated interval (numerical range) includes an unknown.

- Confidence limits. The extremes of a confidence interval.

Source: Nick Ward, Vicechair, IALA e-Nav Committee, March 2009

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