Calculates the lower confidence limits for observed numbers of events using Byar's method [1].
byars_lower(x, confidence = 0.95)
the observed numbers of events; numeric vector; no default
the required level of confidence expressed as a number between 0.9 and 1 or 90 and 100; numeric; default 0.95
Returns lower confidence limits for observed numbers of events using Byar's method [1]
byars_lower
and byars_upper
together return symmetric confidence
intervals around counts, therefore
for a specified confidence level, \(\alpha\), the probability that, by chance, the lower limit returned
will be above the true underlying value, is \(\alpha\)/2.
If the confidence level is very close to 1 or the number of events is very small
Byar's method is inaccurate and may return a negative number - in these cases an error is returned.
[1] Breslow NE, Day NE. Statistical methods in cancer research, volume II: The design and analysis of cohort studies. Lyon: International Agency for Research on Cancer, World Health Organisation; 1987.
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