STATISTICAL LINKS

These are links to statistical resources on the World Wide Web which researchers find most useful. We've tried to select the sites which we felt would be of most interest to non-statisticians. The links are broken down into four categories: online textbooks and general statistical topics, dictionaries and encyclopedias, specific statistical topics, manuscripts, and statistical computing and software. Reports of broken links or suggestions for additional sites would be greatly appreciated.  Please send email to houckpr@upmc.edu.

Online Textbooks and General Statistical Topics

• Statistics Notes from the British Medical Journal. This is a very nice series of articles geared toward clinicians. It covers a broad array of statistical issues, especially those relevant to the analysis of clinical trial data.
• Statnotes from North Carolina State University. Great site with non-technical overviews of a wide variety of statistical techniques and approaches. Most topics are accompanied by guidelines to applying the technique in SPSS.
• Little Handbook of Statistical Practice by Gerald Dallal. This is an engaging introduction to statistical techniques and the practice of statistics written in a conversational style.
• StatManual from the University of Wisconsin - Steven's Point. This is an elementary introduction to applied statistical techniques, with an emphasis on linear models (especially regression, ANOVA and MANOVA). Includes quizzes.
• Intuitive Biostatistics from GraphPad. Several chapters of Harvey Motulsky's book provided as online samples. The chapter on multiple comparisons is especially good.
• Distribution Theory and Statistical Inference from the University of New England, New South Wales, Australia. A good, relatively brief introduction to statistical theory.

Dictionaries and Encyclopedias

• Mathworld by Eric Weisstein. Comprehensive mathematical dictionary compiled from public contributions. Has a good selection of topics in probability and (to a somewhat lesser extent) statistics.
• The Data Analysis BriefBook from CERN. A fairly thorough dictionary of statistical terms and concepts.

Specific Statistical Topics

• Exploratory Data Analysis from the National Institute of Standards and Technology. The overview provides a broad introduction to this important topic. Its alphabetical index of graphical techniques is particularly nice.
• Item Response Theory from EdRes.org. Contains tutorials and software for item response theory and computer adaptive testing, as well as a self-contained online textbook for IRT.
• Multilevel Data Analysis from Don Hedecker at University of Illinois at Chicago. Includes PDF files, datasets, examples, and programs.

Manuscripts

• Kraemer HC. DSM categories and dimensions in clinical and research contexts. Int J Methods Psychiatr Res. 2007;16 Suppl 1 2007:S8-S15.
• Kraemer HC, Shrout PE, Rubio-Stipec M. Developing the diagnostic and statistical manual V: what will "statistical" mean in DSM-V? Soc Psychiatry Psychiatr Epidemiol. 2007 Apr;42(4):259-67.
• Kraemer HC. Correlation coefficients in medical research: from product moment correlation to the odds ratio. Stat Methods Med Res. 2006 Dec;15(6):525-45.
• Kraemer HC, Frank E, Kupfer DJ. Moderators of treatment outcomes: clinical, research, and policy importance. JAMA. 2006 Sep 13;296(10):1286-9. 
• Helzer JE, Kraemer HC, Krueger RF. The feasibility and need for dimensional psychiatric diagnoses. Psychol Med. 2006 Dec;36(12):1671-80. 
• Kraemer HC, Mintz J, Noda A, Tinklenberg J, Yesavage JA. Caution regarding the use of pilot studies to guide power calculations for study proposals. Arch Gen Psychiatry. 2006 May;63(5):484-9.
• Kraemer HC. A simple effect size indicator for two-group comparisons? A comment on r equivalent. Psychol Methods. 2005 Dec;10(4):413-9. 
• Kraemer HC, Kupfer DJ. Size of treatment effects and their importance to clinical research and practice. Biol Psychiatry. 2006 Jun 1;59(11):990-6.
• Kraemer HC, Robinson TN. Are certain multicenter randomized clinical trial structures misleading clinical and policy decisions? Contemp Clin Trials. 2005 Oct;26(5):518-29.
• Kraemer HC, Blasey CM. Centring in regression analyses: a strategy to prevent errors in statistical inference. Int J Methods Psychiatr Res. 2004;13(3):141-51.
• Kraemer HC. Reconsidering the odds ratio as a measure of 2x2 association in a population. Stat Med. 2004 Jan 30;23(2):257-70. 
• Kraemer HC, Noda A, O'Hara R. Categorical versus dimensional approaches to diagnosis: methodological challenges. J Psychiatr Res. 2004 Jan;38(1):17-25.
• Kraemer HC, Morgan GA, Leech NL, Gliner JA, Vaske JJ, Harmon RJ. Measures of clinical significance. J Am Acad Child Adolesc Psychiatry. 2003 Dec;42(12):1524-9.
• Kraemer HC. "Rules" of evidence in assessing the efficacy and effectiveness of treatments. Dev Neuropsychol. 2003;24(2-3):705-18.
• Kraemer HC, Measelle JR, Ablow JC, Essex MJ, Boyce WT, Kupfer DJ. A new approach to integrating data from multiple informants in psychiatric assessment and research: mixing and matching contexts and perspectives. Am J Psychiatry. 2003 Sep;160(9):1566-77.
• Kraemer HC, Schultz SK, Arndt S. Biomarkers in psychiatry: methodological issues. Am J Geriatr Psychiatry. 2002 Nov-Dec;10(6):653-9.
• Kraemer HC, Wilson GT, Fairburn CG, Agras WS. Mediators and moderators of treatment effects in randomized clinical trials. Arch Gen Psychiatry. 2002 Oct;59(10):877-83.
• Kraemer HC, Stice E, Kazdin A, Offord D, Kupfer D. How do risk factors work together? Mediators, moderators, and independent, overlapping, and proxy risk factors. Am J Psychiatry. 2001 Jun;158(6):848-56. 
• Kiernan M, Kraemer HC, Winkleby MA, King AC, Taylor CB. Do logistic regression and signal detection identify different subgroups at risk? Implications for the design of tailored interventions. Psychol Methods. 2001 Mar;6(1):35-48. 
• Kraemer HC. Pitfalls of multisite randomized clinical trials of efficacy and effectiveness. Schizophr Bull. 2000;26(3):533-41. 
• Schatzberg AF, Kraemer HC. Use of placebo control groups in evaluating efficacy of treatment of unipolar major depression. Biol Psychiatry. 2000 Apr 15;47(8):736-44.
• Kraemer HC. Statistical analysis to settle ethical issues? Arch Gen Psychiatry. 2000 Apr;57(4):327-8.
• Kraemer HC, Yesavage JA, Taylor JL, Kupfer D. How can we learn about developmental processes from cross-sectional studies, or can we? Am J Psychiatry. 2000 Feb;157(2):163-71.
• Spiegel D, Kraemer HC, Bloom JR. A tale of two methods: randomization versus matching trials in clinical research. Psychooncology. 1998 Sep-Oct;7(5):371-5.
• Kraemer HC. What is the 'right' statistical measure of twin concordance (or diagnostic reliability and validity)? Arch Gen Psychiatry. 1997 Dec;54(12):1121-4.
• Kraemer HC, Kazdin AE, Offord DR, Kessler RC, Jensen PS, Kupfer DJ. Coming to terms with the terms of risk. Arch Gen Psychiatry. 1997 Apr;54(4):337-43.

Statistical Computing and Software

• Schematic from the Department of Psychiatry, University of Pittsburgh. A program for classifying and diagramming Mediators, moderators, and independent, proxy and overlapping risk factors.
• StatLib from Carnegie Mellon University. Probably the best all-around source for statistical software and public domain datasets.
• Statistical Computing Resources from UCLA. This is a great collection of examples, instructions, and tutorials for conducting analyses using standard statistical software packages. The coverage of SAS, SPSS and Stata is particularly good, but there's also information about several other packages.
• The Comprehensive R Archive Network (CRAN). Distribution source for the software package R, as well as add-on packages and documentation. R is an extremely flexible and powerful (and free!) statistical software package, largely compatible with S-Plus.
• Statpages. A really cool (and amazingly large) set of links to online statistical calculators for everything from fitting linear models to running survival analyses to performing power calculations and randomizing subjects. Not frequently updated - be prepared for broken links.
• SAS OnlineDoc. Online documentation for SAS. Also contains a fair amount of general-interest statistical information.
• TETRAD. An interesting program for exploring causal relationships in data.
• Causal and Statistical Reasoning homepage from Carnegie Mellon University. More tools for causal explorations.
• OSWALD (Object-oriented SoftWare for the Analysis of Longitudinal Data). S-Plus library with a variety of functions for analyzing longitudinal data, including the modeling of dropout mechanisms. Works with S-Plus 4.5 and 2000.
• MPlus from Muthén and Muthén. Homepage for the software package for random effect, factor, and latent class analysis.
• ASTSA from David Stoffer, Department of Statistics, University of Pittsburgh. Software for time series modeling and graphing from
• Multiple-Imputation.com. Collection of software for using multiple imputation techniques for statistical analysis in the presence of missing data.
• Effect Size Calculators from the University of Colorado - Colorado Springs. Provides two simple online calculators for computing Cohen's d effect size index.

Updated 11/19/09 CK