eclpci



Stata help for eclpci

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help for eclpci
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Exact and Approximate Confidence Limits for Poisson Counts

eclpci #obs [#exp] [ , level(#) format(%fmt) normal nccorr rb chi2 chi2c ]

where

#obs observed number of events [#exp] expected number of events

Description

eclpci calculates exact and approximate confidence limits for a Poisson count (#obs). It provides a Standardized Mortality Ratio (SMR=#obs/#exp) and its confidence limits if the expected number of events (#exp) is specified. It is an immediate command. Options

level(#) specifies the width of the confidence interval; see help level.

format(%fmt) specifies the display format for presenting numbers. format(%4.3f) is the default; see help format.

normal specifies the normal approximation to calculate confidence limits of the counts (or SMR).

nccorr specifies the normal approximation with continuity correction to calculate confidence limits of the counts (or SMR).

rb specifies approximate limits of the counts (or SMR) as described by Rothman and Boyce (1979) or Breslow and Day (1987)

chi2 specifies a chi-square with simple continuity correction (eq. 2.10 pag.68, Breslow and Day, 1987)

chi2c specifies chi-square with a better approximation to the exact Poisson test (eq. 2.12 pag.69, Breslow and Day, 1987)

Examples

* some examples are extracted from Table 2 page 356 of Daly L. (1992)

. eclpci 1 . eclpci 10 . eclpci 50 . eclpci 100 . eclpci 1, ncc . eclpci 10, ncc . eclpci 50, n . eclpci 100, ncc

. eclpci 18 27.07 . eclpci 18 27.07, f(%5.4f) rb

References

Daly, L., Simple SAS macros for the calculation of exact binomial and Poisson confidence limits, Comput Biol Med 22:351-361, 1992.

Breslow NE, Day NE., Statistical Methods in Cancer Research: Volume II, The Design and Analysis of Cohort Studies. Lyon: International Agency for Research on Cancer, 1987, p.69.

Rothman KJ., and Boice JD., Epidemiologic Analysis with a Programmable Calculator (NIH Publication 79-1649), Washington DC, US Government Printing Office, 1979.

Guidelines for Using Confidence Intervals for Public Health Assessment http://www.doh.wa.gov/Data/Guidelines/WordDocs/CI_guidelines.pdf

Support

http://nicolaorsini.altervista.org

Worked examples for eclpci

Click here to run or save the do-file

. capture net install http://nicolaorsini.altervista.org/stata/eclpci

. . which eclpci c:\ado\stbplus\e\eclpci.ado *! N.Orsini v.1.0.0 04May2005

. . * some examples are extracted from Table 2 page 356 of Daly L. (1992) . . eclpci 1

Observed counts: 1 95% CI[0.025, 5.572]

. eclpci 10

Observed counts: 10 95% CI[4.795, 18.390]

. eclpci 50

Observed counts: 50 95% CI[37.111, 65.919]

. eclpci 100

Observed counts: 100 95% CI[81.364, 121.627]

. eclpci 1, ncc

Observed counts: 1 95% CI[0.000, 3.920]

. eclpci 10, ncc

Observed counts: 10 95% CI[4.762, 17.158]

. eclpci 50, n

Observed counts: 50 95% CI[36.141, 63.859]

. eclpci 18 27.07

SMR: 0.665 95% CI[0.394, 1.051]

. eclpci 18 27.07, f(%5.4f) rb

SMR: 0.6649 95% CI[0.3939, 1.0510]


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