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 I’ve 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.
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Noncentral F files |
Noncentral t files |
Noncentral Chi-square files |
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Download NoncF3.sps |
Download NoncT2.sps |
Download NoncChi.sps |
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Download NoncF.sav |
Download NoncT.sav |
Download NoncChi.sav |
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Download F2R2.sps |
Download T2D.sps |
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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.
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Noncentral F file |
Noncentral t files |
Noncentral Chi-square files |
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Download NoncF2.sas |
Download Nonct.sas |
Download Noncchi.sas |
| Download t2d1samp.sas | Download CramersV.sas | |
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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.
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Noncentral F file |
Noncentral t files |
Noncentral Chi-square file |
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Download Fscript.SSC |
Download Nonct.SSC |
Download Chiscript.SSC |
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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:
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
