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Back to the forum  2018-06-22 19:27 CEST (UTC+2h)

confint() for difference of effect levels [R for BE/BA]

posted by d_labes - Berlin, Germany, 2017-08-29 12:23  - Posting: # 17749
Views: 2,334

Dear Öberster Größter Meister,

» let us say we have an lm object for a BE analysis in a study where we have n treatments.
Ok. I assume we have.

» Is there a way to use confint() to derive CI's for the difference of the i'th and j'th treatments (where obviously i!=j, and i is within 1..n and j is within 1..n) ?
No. confint() gives you confidence intervals for the model parameters only.

» If not, is there another built-in function that achieves this goal?
Built in I know of none, if you mean a base R installation. Only from add-on packages.
Have a look at package multcomp.
Or if you prefer using such beasts like "least square means" have a look at package lsmeans.

BTW: All-at-once is not the preferred method of a big regulatory body.
Pairwise lm objects (throwing away the data under those treatments not under consideration) will give you the opportunity to use confint() to derive CI's.



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