Scripts and Software for Noncentral Confidence Interval and Power Calculations

This webpage contains download links for scripts that enable you to compute confidence intervals and power based on the noncentral t, F, and Chi-square distributions. So far, these are available in SPSS, SPlus, and R. I will update this webpage with links to other freeware and/or scripts as they become available and known to me.

A general (but not expensive!) reference on confidence intervals that covers noncentral confidence interval estimation, as well as the more well-known confidence intervals, is:

Smithson, M.J. (2003). Confidence Intervals,
Quantitative Applications in the Social Sciences Series, No. 140.
Thousand Oaks, CA: Sage.

 

 

SPSS Scripts

There is a PDF file based on a short workshop Iíve given on noncentral confidence intervals that includes instructions on how to use these scripts. This will have to do as an instruction manual until I write a more thorough-going version.

Download PDF file.

Noncentral F files

Noncentral t files

Noncentral Chi-square files

Download NoncF3.sps

Download NoncT2.sps

Download NoncChi.sps

Download NoncF.sav

Download NoncT.sav

Download NoncChi.sav

Download F2R2.sps

Download T2D.sps

 

 

SAS Scripts

These scripts come with a "Readme" PDF file. Users not familiar with noncentral confidence intervals may also wish to download the workshop instructional PDF file mentioned above.

Download Readme file.

Noncentral F file

Noncentral t files

Noncentral Chi-square files

Download NoncF2.sas

Download Nonct.sas

Download Noncchi.sas

Download t2d1samp.sas Download CramersV.sas

 

Download t2d2samp.sas

 

SPlus and R Scripts

These scripts come with a "Readme" PDF file. Users not familiar with noncentral confidence intervals may also wish to download the workshop instructional PDF file mentioned above.

Download Readme file.

Noncentral F file

Noncentral t files

Noncentral Chi-square file

Download Fscript.SSC

Download Nonct.SSC

Download Chiscript.SSC

 

Download Rknonct.SSC

 

 

Links to More Software

Some great software that runs under Excel dealing with confidence intervals in general, and also with confidence intervals for effect sizes, is the Exploratory Software for Confidence Intervals (ESCI--pronounced "es-key") software developed by Geoff Cumming:

www.psy.latrobe.edu.au/esci

Jim Steiger and Rachael Fouladi (1992) have provided very useful program called "R2" that computes confidence intervals and power for multiple and partial R-squared. This program runs in DOS and can be downloaded from:

http://www.interchg.ubc.ca/steiger/homepage.htm

For Statistica users, information about an add-on module for computing noncentral confidence intervals and power may be found at:

http://www.statsoft.com/power_an.html

 

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