Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Parameter estimates of model C and their 95% confidence intervals. The parameters were estimated independently for four time periods of similar length (the earliest period is somewhat longer in order to avoid estimation problems): cod year-classes 1921–1942; 1943–1961; 1962–1980; and 1981–1999 (indicated by the shaded boxes).
