Mortality Estimation: Biased Results from Unbiased Ages

Jay Barlow
1984 Canadian Journal of Fisheries and Aquatic Sciences  
Estimates of mortality rates from age distributions are biased by imprecision in age estimation, even if age estimates are unbiased. I have derived a method for predicting the magnitude of this bias from information on the precision of age determination. Monte Carlo simulations show that bias can be accurately predicted. The commonly used Chapman-Robson mortality estimator is shown to be robust to imprecision in age determination if all age-classes are included. Errors are likely, however, if
more » ... e or more age-classes are excluded or if other mortality estimators are used. Biases can be corrected if the distribution of ageestimation errors is known.
doi:10.1139/f84-227 fatcat:4barfkauvfd4tlwj4rrp5vrsjm