Epi (version 2.56)

apc.frame: Produce an empty frame for display of parameter-estimates from Age-Period-Cohort-models.

Description

A plot is generated where both the age-scale and the cohort/period scale is on the x-axis. The left vertical axis will be a logarithmic rate scale referring to age-effects and the right a logarithmic rate-ratio scale of the same relative extent as the left referring to the cohort and period effects (rate ratios).

Only an empty plot frame is generated. Curves or points must be added with points, lines or the special utility function apc.lines.

Usage

apc.frame( a.lab,
            cp.lab,
             r.lab,
            rr.lab = r.lab / rr.ref,
            rr.ref = r.lab[length(r.lab)/2],
             a.tic = a.lab,
            cp.tic = cp.lab,
             r.tic = r.lab,
            rr.tic = r.tic / rr.ref,
           tic.fac = 1.3,
             a.txt = "Age",
            cp.txt = "Calendar time",
             r.txt = "Rate per 100,000 person-years",
            rr.txt = "Rate ratio",
          ref.line = TRUE,
               gap = diff(range(c(a.lab, a.tic)))/10,
          col.grid = gray(0.85),
             sides = c(1,2,4) )

Value

A numerical vector of length two, with names

c("cp.offset","RR.fac"). The first is the offset for the cohort period-axis, the second the multiplication factor for the rate-ratio scale.

Side-effect: A plot with axes and grid lines but no points or curves. Moreover, the option apc.frame.par is given the value

c("cp.offset","RR.fac"), which is recognized by apc.plot

and apc.lines.

Arguments

a.lab

Numerical vector of labels for the age-axis.

cp.lab

Numerical vector of labels for the cohort-period axis.

r.lab

Numerical vector of labels for the rate-axis (left vertical)

rr.lab

Numerical vector of labels for the RR-axis (right vertical)

rr.ref

At what level of the rate scale is the RR=1 to be.

a.tic

Location of additional tick marks on the age-scale

cp.tic

Location of additional tick marks on the cohort-period-scale

r.tic

Location of additional tick marks on the rate-scale

rr.tic

Location of additional tick marks on the RR-axis.

tic.fac

Factor with which to diminish intermediate tick marks

a.txt

Text for the age-axis (left part of horizontal axis).

cp.txt

Text for the cohort/period axis (right part of horizontal axis).

r.txt

Text for the rate axis (left vertical axis).

rr.txt

Text for the rate-ratio axis (right vertical axis)

ref.line

Logical. Should a reference line at RR=1 be drawn at the calendar time part of the plot?

gap

Gap between the age-scale and the cohort-period scale

col.grid

Colour of the grid put in the plot.

sides

Numerical vector indicating on which sides axes should be drawn and annotated. This option is aimed for multi-panel displays where axes only are put on the outer plots.

Author

Bendix Carstensen, Steno Diabetes Center, http://bendixcarstensen.com

Details

The function produces an empty plot frame for display of results from an age-period-cohort model, with age-specific rates in the left side of the frame and cohort and period rate-ratio parameters in the right side of the frame. There is a gap of gap between the age-axis and the calendar time axis, vertical grid lines at c(a.lab,a.tic,cp.lab,cp.tic), and horizontal grid lines at c(r.lab,r.tic).

The function returns a numerical vector of length 2, with names c("cp.offset","RR.fac"). The y-axis for the plot will be a rate scale for the age-effects, and the x-axis will be the age-scale. The cohort and period effects are plotted by subtracting the first element (named "cp.offset") of the returned result form the cohort/period, and multiplying the rate-ratios by the second element of the returned result (named "RR.fac").

References

B. Carstensen: Age-Period-Cohort models for the Lexis diagram. Statistics in Medicine, 26: 3018-3045, 2007.

See Also

apc.lines,apc.fit

Examples

par( mar=c(4,4,1,4) )
res <-
apc.frame( a.lab=seq(30,90,20), cp.lab=seq(1880,2000,30), r.lab=c(1,2,5,10,20,50),
           a.tic=seq(30,90,10), cp.tic=seq(1880,2000,10), r.tic=c(1:10,1:5*10),
           gap=27 )
res
# What are the axes actually?
par(c("usr","xlog","ylog"))
# How to plot in the age-part: a point at (50,10)
points( 50, 10, pch=16, cex=2, col="blue" )
# How to plot in the cohort-period-part: a point at (1960,0.3)
points( 1960-res[1], 0.3*res[2], pch=16, cex=2, col="red" )
# or referring to the period-cohort part of the plot 
pc.points( 1960, 0.3, pch=16, cex=1, col="green" )