HH: odds.ratio – R documentation

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odds.ratio

Calculate or plot the odds ratio for a 2x2 table of counts.

Description

Calculate or plot the odds ratio for a 2x2 table of counts. The plot shows the confidence intervals on the probability of row2 for fixed odds ratio and specified probability for row1.

Usage

OddsRatio(x, alpha = 0.05)

plotOddsRatio(x,
              ylab="prob(col1 | row1)",
              xlab="prob(col1 | row2)",
              alpha=c(.50, .05),
              col=trellis.par.get("superpose.line")$col,
              lwd=trellis.par.get("superpose.line")$lwd,
              lwd.reference=1,
              ...)

plotOddsRatio.base(x,
 ylab = "prob(col1 | row1)", xlab = "prob(col1 | row2)",
 alpha = c(0.05, 0.5),
 legend.x=1.05,
 oma=c(0,0,0,5), ...)

Arguments

`x`	2 x 2 table of counts
`alpha`	Significance levels of test. `OddsRatio` requires a single number in the range [0,1]. `plotOddsRatio` accepts more than one number on the range [0,1] and draws confidence lines at each value.
`xlab, ylab`	x- and y-labels for the plot Sensible defaults are generated.
`col, lwd`	Colors and linewidths to be used in the graph.
`lwd.reference`	linewidth for reference line.
`...`	other arguments, currently ignored.
`legend.x`	x position of left-hand side of legend.
`oma`	outer margin `par()$oma`, needed to make room for legend.

Value

plotOddsRatio returns a lattice object.

The older plotOddsRatio.base draws a plot with base graphics and invisibly returns the same list as OddsRatio returns for the first value of alpha.

OddsRatio returns the list:

`p1, p2`	proportion of each row total observed in the first column.
`omega1, omega2`	odds for each row, p/(1-p)
`psihat`	odds ratio, omega2/omega1
`s.ln.psihat`	standard deviation of `ln(psihat)`
`ci.ln.psihat`	confidence interval for `ln(psihat)` using normal approximation
`ci.psihat`	confidence interval for `psihat` calculated ase `p(ci.ln.psihat)`
`prob1`	`seq(0,1,.05)`, set of p1 values for plotting.
`odds1`	`p1/(1-p1)`
`odds2`	odds for the second row needed to retain `psihat` with the specified `odds1`, calculated as `odds1*psihat`.
`ci.odds2`	confidence interval for `odds2`
`prob2`	`odds2 / (odds2+1)`
`ci.prob2`	`ci.odds2 / (ci.odds2+1)`

Author(s)

Richard M. Heiberger <rmh@temple.edu>

References

Heiberger, Richard M. and Holland, Burt (2015). Statistical Analysis and Data Display: An Intermediate Course with Examples in R. Second Edition. Springer-Verlag, New York. https://www.springer.com/us/book/9781493921218

Examples

data(glasses)

## draw the iso-odds ratio plot with 50% CI and 95% CI,
plotOddsRatio(glasses)

## return the 95% CI information
OddsRatio(glasses)

## draw the iso-odds ratio plot with 50% CI and 95% CI,
## invisibly return the 95% CI information
plotOddsRatio.base(glasses)

HH

Statistical Analysis and Data Display: Heiberger and Holland

v3.1-43

GPL (>= 2)

Authors

Richard M. Heiberger

Initial release

2020-11-27