Dynamic Tomography Plot
dtomogplot is used to produce a tomography plot (see King, 1997) for a series of temporally ordered, partially observed 2 x 2 contingency tables.
dtomogplot( r0, r1, c0, c1, time.vec = NA, delay = 0, xlab = "fraction of r0 in c0 (p0)", ylab = "fraction of r1 in c0 (p1)", color.palette = heat.colors, bgcol = "black", ... )
r0 |
An (ntables \times 1) vector of row sums from row 0. |
r1 |
An (ntables \times 1) vector of row sums from row 1. |
c0 |
An (ntables \times 1) vector of column sums from column 0. |
c1 |
An (ntables \times 1) vector of column sums from column 1. |
time.vec |
Vector of time periods that correspond to the elements of r_0, r_1, c_0, and c_1. |
delay |
Time delay in seconds between the plotting of the tomography lines. Setting a positive delay is useful for visualizing temporal dependence. |
xlab |
The x axis label for the plot. |
ylab |
The y axis label for the plot. |
color.palette |
Color palette to be used to encode temporal patterns. |
bgcol |
The background color for the plot. |
... |
further arguments to be passed |
Consider the following partially observed 2 by 2 contingency table:
| Y=0 | | Y=1 | | | |
--------- | --------- | --------- | --------- |
X=0 | | Y_0 | | | | r_0 |
--------- | --------- | --------- | --------- |
X=1 | | Y_1 | | | | r_1 |
--------- | --------- | --------- | --------- |
| c_0 | | c_1 | | N |
where r_0, r_1, c_0, c_1, and N are non-negative integers that are observed. The interior cell entries are not observed. It is assumed that Y_0|r_0 \sim \mathcal{B}inomial(r_0, p_0) and Y_1|r_1 \sim \mathcal{B}inomial(r_1, p_1).
This function plots the bounds on the maximum likelihood estimates for (p0, p1) and color codes them by the elements of time.vec.
Gary King, 1997. A Solution to the Ecological Inference Problem. Princeton: Princeton University Press.
Jonathan C. Wakefield. 2004. “Ecological Inference for 2 x 2 Tables.” Journal of the Royal Statistical Society, Series A. 167(3): 385445.
Kevin Quinn. 2004. “Ecological Inference in the Presence of Temporal Dependence." In Ecological Inference: New Methodological Strategies. Gary King, Ori Rosen, and Martin A. Tanner (eds.). New York: Cambridge University Press.
## Not run: ## simulated data example 1 set.seed(3920) n <- 100 r0 <- rpois(n, 2000) r1 <- round(runif(n, 100, 4000)) p0.true <- pnorm(-1.5 + 1:n/(n/2)) p1.true <- pnorm(1.0 - 1:n/(n/4)) y0 <- rbinom(n, r0, p0.true) y1 <- rbinom(n, r1, p1.true) c0 <- y0 + y1 c1 <- (r0+r1) - c0 ## plot data dtomogplot(r0, r1, c0, c1, delay=0.1) ## simulated data example 2 set.seed(8722) n <- 100 r0 <- rpois(n, 2000) r1 <- round(runif(n, 100, 4000)) p0.true <- pnorm(-1.0 + sin(1:n/(n/4))) p1.true <- pnorm(0.0 - 2*cos(1:n/(n/9))) y0 <- rbinom(n, r0, p0.true) y1 <- rbinom(n, r1, p1.true) c0 <- y0 + y1 c1 <- (r0+r1) - c0 ## plot data dtomogplot(r0, r1, c0, c1, delay=0.1) ## End(Not run)
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