# or.midp: Odds ratio estimation and confidence intervals using mid-p... In epitools: Epidemiology Tools

## Description

Calculates odds ratio by median-unbiased estimation and exact confidence interval using the mid-p method (Rothman 1998).

## Usage

 `1` ```or.midp(x, conf.level = 0.95, byrow = TRUE, interval = c(0, 1000)) ```

## Arguments

 `x` input data can be 2x2 matrix or vector of length 4 `conf.level` confidence level (default is 0.95) `byrow` integer vectors are read in row-wise (default) `interval` interval for the `uniroot` that finds the odds ratio median-unbiased estimate and mid-p exact confidence interval for `oddsratio.midp`

## Details

Calculates odds ratio by median-unbiased estimation and exact confidence interval using the mid-p method (Rothman 1998, p. 251).

This function expects the following 2x2 table struture:

 ```1 2 3 4``` ``` exposed not exposed disease a1 a0 no disease b1 b0 ```

or a numeric vector of the form c(a1, a0, b1, b0).

This function is used by `oddsratio.midp`.

## Value

 `x` table that was used in analysis `data` same table as `x` but with marginal totals `estimate` median unbiased odds ratio `conf.level` confidence level used

## Author(s)

Tomas Aragon, [email protected], http://www.phdata.science

## References

Kenneth J. Rothman and Sander Greenland (1998), Modern Epidemiology, Lippincott-Raven Publishers

`oddsratio`

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10``` ```##rothman p. 243 z1 <- matrix(c(12,2,7,9),2,2,byrow=TRUE) z2 <- z1[2:1,2:1] ##jewell p. 79 z3 <- matrix(c(347,555,20,88),2,2,byrow=TRUE) z4 <- z3[2:1,2:1] or.midp(z1) or.midp(z2) or.midp(z3) or.midp(z4) ```

### Example output

```\$x
[,1] [,2]
[1,]   12    2
[2,]    7    9

\$estimate
[1] 6.880701

\$conf.int
[1]  1.276258 60.721998

\$conf.level
[1] 0.95

attr(,"method")
[1] "median-unbiased estimate & mid-p exact CI"
\$x
[,1] [,2]
[1,]    9    7
[2,]    2   12

\$estimate
[1] 6.880701

\$conf.int
[1]  1.276258 60.721998

\$conf.level
[1] 0.95

attr(,"method")
[1] "median-unbiased estimate & mid-p exact CI"
\$x
[,1] [,2]
[1,]  347  555
[2,]   20   88

\$estimate
[1] 2.732458

\$conf.int
[1] 1.683370 4.648361

\$conf.level
[1] 0.95

attr(,"method")
[1] "median-unbiased estimate & mid-p exact CI"
\$x
[,1] [,2]
[1,]   88   20
[2,]  555  347

\$estimate
[1] 2.732458

\$conf.int
[1] 1.683370 4.648361

\$conf.level
[1] 0.95

attr(,"method")
[1] "median-unbiased estimate & mid-p exact CI"
```

epitools documentation built on May 29, 2017, 3:40 p.m.