The inter-annual variability of a time series stored in an FLQuant object, is computed as \(|x_y - x_{y-1}) / x_{y-1}|\). The resulting object will be one year shorter than the input. The first year will be missing as values are assigned to the final year of each pair.
Examples
data(ple4)
# Compute inter-annual variability in catch
iav(catch(ple4))
#> An x of class "FLQuant"
#> , , unit = unique, season = all, area = unique
#>
#> year
#> age 1958 1959 1960 1961 1962 1963 1964 1965 1966
#> all 0.13304 0.18473 0.12158 0.01328 0.05646 0.11501 0.04776 0.02621 0.07172
#> year
#> age 1967 1968 1969 1970 1971 1972 1973 1974 1975
#> all 0.04802 0.03013 0.02431 0.06539 0.03372 0.05781 0.01422 0.04276 0.04682
#> year
#> age 1976 1977 1978 1979 1980 1981 1982 1983 1984
#> all 0.06342 0.05707 0.07430 0.03095 0.06973 0.00106 0.04306 0.10493 0.07352
#> year
#> age 1985 1986 1987 1988 1989 1990 1991 1992 1993
#> all 0.08239 0.13015 0.10476 0.02193 0.07362 0.14187 0.12937 0.11684 0.06808
#> year
#> age 1994 1995 1996 1997 1998 1999 2000 2001 2002
#> all 0.15773 0.12311 0.00686 0.15545 0.12514 0.00338 0.14452 0.12254 0.12256
#> year
#> age 2003 2004 2005 2006 2007 2008 2009 2010 2011
#> all 0.07108 0.09072 0.18211 0.02345 0.06342 0.08234 0.02034 0.02698 0.00752
#> year
#> age 2012 2013 2014 2015 2016 2017
#> all 0.10152 0.06964 0.00925 0.01726 0.04458 0.04797
#>
#> units: