Full Contents Short Contents: Preface: About These Pages Summarizing Data Simple Statistics & Effect Statistics Dimension Reduction Precision of Measurement Generalizing to a Population Confidence Limits & Statistical Significance Statistical Models Estimating Sample Size Summary: The Most Important Points Quiz Reference: Hopkins,
W. G. (2000). A new view of statistics. Internet Society for Sport Science:
http://www.sportsci.org/resource/stats/.If you are viewing this page without a navigation/index frame on the left, click here. Go to: Preface · Contents · Start of Text · Search · Home UPDATES2013 May. Coming very soon: a slideshow and Excel workbook for an introductory course of 10 lectures on statistics. Actually it is available. Contact me.2011 Aug. Check out the following 2010 articles at Sportscience: assigning subjects to treatments in a controlled trial; regression vs limits of agreement in measure-comparison studies; magnitudes of effects derived from linear models. See the frame
at right for links to much more, including the progressive
statistics and research design articles.. 2009Dec 8. Progressive statistics now available as a complete updated article. May 23-29. Much improved reliability
spreadsheet. A spreadsheet
for the intraclass correlation coefficient, and some updating
of page on reliability calculations. May 17. Progressive
Statistics Updated in Sportscience
2009 for more information on a complete guide to statistical
analysis and presentation. May 16. April 9. Sorry, folks,
I continue to neglect these pages in favor of peer-reviewed articles
at. See
the 2008 In-Brief column for
a comprehensive slideshow on statistical guidelines and an
article in the same issue on research designs. 2008 June 15. Frame added at right
for easier access to main stats resources. Zipped copy of these pages no
longer available, because there are too many good resources at Sportscience.
Jan 4. See 2007 issue
of Sportscience for learning
stats with spreadsheets, clinical
and mechanistic inferences via p values, a new spreadsheet for comparing
group means, and sample-size
updates. For history of previous updates, see
below.2007 Nov
18: Fixed error in formulae for adjusting to value of covariate in the
repeated-measures (controlled-trials) spreadsheets.
Retirement looms... Tweaked the bootstrapping
example. Oct 21: Spreadsheet for confidence limits
now generates customizable clinical and mechanistic inferences. Oct 14: Papers and spreadsheets for analysis of controlled trials, combining
independent estimates, and estimation of sample-size in the 2006 issue of
Sportscience. Other
useful stats stuff in the In-brief section there, too.Jan 4: 2006 Oct 8: Minor additions to validity
spreadsheet. New way of justifying thresholds for magnitudes
of standardized differences in means. Aug 7: Latest sample-size resources at sportsci.org/2006.
I will update the pages here eventually. July 5: Error in ICC formulae now corrected in spreadsheet
for reliability. Sorry about that, folks. May 12 : Spreadsheet for reliability
now has stats averaged over multiple trials. Mar 22: 2005Dec 16: Updates long overdue. Meanwhile
check Sportscience for articles
on magnitude-based inferences, controlled
trials, meta-analysis, interpreting
test results, and a critique of Bland-Altman
validity. June 25: Validity spreadsheet now
has confidence limits for parameters of calibration equation. Corrected residuals in log section of validity
spreadsheet. June 2: 2004 Aug 19: Info about generalized linear
modeling for variables representing counts and proportions.2003 Nov 1: Article and spreadsheets
for analysis of straightforward controlled trials, crossovers, and time
series. Adjustable level for confidence limits added to reliability
and validity spreadsheets. Oct 10: Minor improvement to Mean ± SD
or Mean ± SEM? June 25: Correcting change scores
and other updates of regression to the mean.
June 15: Slideshow on repeated measures.
Tweaking of categorical modeling and most pages
on repeated measures. New section on repeated
measures with troublesome variables. June 8: More on uniformity of residuals,
especially in complex models,
and more on Cohen effects via rank transformation.
Mar 9: Spreadsheet for assessing
an individual now includes qualitative clinical chances. Jan 31: Confidence limits as ± and x/÷ added to spreadsheet.
Jan 23: Minor tweaking of transformations for
counts and proportions. Caution about back-transformed
means. Jan 16: 2002Dec 4: Clinical/practical significance updates of spreadsheet
now complete. probabilities of clinical/practical significance added to spreadsheet.
Nov 3: Clinical vs statistical significance: Powerpoint
presentation and link to new article. June 29: Powerpoint presentation on covariates
in repeated-measures analyses. Update of controlling
for something, and a new section on mechanism
variables and confounders. June 4: Clearer explanations of transformations
for counts and proportions. Minor tweaking of scale
of effect magnitudes. May 6: Regression to the mean. Apr 29: Confidence limits for relative risk and odds ratio included
in spreadsheet. Apr 28: Corrected interpretation of odds ratio.
Mar 16: 2001Dec 28: Clinical vs statistical
significance, and updated spreadsheet
for likelihoods of clinically important effects.Aug 20: An exact new-prediction error
to replace the PRESS-derived statistic; spreadsheets for validity
studies and assessing an individual
updated accordingly. Clarification of sample size based on confidence
limits. Minor updates of sample size estimation
and applications of reliability. Aug 5: Jun 4: Powerpoint
presentation on reliability and some of its uses. Update of monitoring
for a change in an individual. Update of spreadsheet
for monitoring/assessing individuals, including (for what it's worth) Bayesian
adjustment.Mar 26: More on degrees of freedom.
Calculation of confidence
limits and p values, including effects of violations of independence
of observations, normality of sampling
distribution, and uniformity of
residuals. Definition of degrees
of freedom. More on t tests with unequal
variances. Substantial changes to log and
rank transformation, and ordinal
and count dependent variables. Mar 3-4: Simple way to estimate practice
effect in a crossover.Mar 2: Variables representing counts.
Mar 1: 2000 Dec 17-19: Counts and proportions
as dependent variables, including binomial and Poisson regressions,
square-root and arcsine-root transformations. Standardized regression coefficient.
More on goodness of fit, t
test, difference in means, relative
frequency, polynomial coefficients and
bad residuals. Dec 10-11: Use of ±
and ×/÷ with typical error. More on log
transformation. Dec 3-5: More on using reliability to estimate
sample size and assess an individual
(plus an upgrade of the spreadsheet).
Sept 11-12: Very cool Google search form added.
Aug 11: Fixed missing-value bug in log plots in reliability
spreadsheet. Aug 4: More on Type O error and one-tailed
tests. June 29: Search form added. June 24: A reprieve for one-tailed
tests, sort of. June 18: Major revisions/new pages for precision
of measurement: measures
of reliability, applications
of reliability, measures
of validity and applications
of validity, plus a spreadsheet
for precision of assessment of individuals. June 15-22: Update of validity,
including an improvement on the PRESS
statistic and a spreadsheet
to analyze simple validity studies.June 4: Apr 15-18:
Bayesian analysis,
and definitions of probability.Mar 31: Type 0 error
and cumulative Type
0 error.Mar 28: Update and simplification of reliability
calculations, plus a spreadsheet!Mar 27: Update of sample-size
estimation, and definition of concurrent
reliability.Mar 26: Rewrite of confidence
intervals and statistical significance, and a
cool way to interpret
the p value.Feb 7: Review
of this site and other stats sites at BioMedNet.1999 June 17: More on interpreting
sex in a two-way ANOVA. New section on sex
in repeated measures.May 27: Slideshow
on confidence limits.May 22: New features in spreadsheet
for confidence limits (ratio of standard deviations, and Tate & Klett
adjustment for standard deviations).1998Dec 6: Tidy-up of reliability, reliability calculations, validity, and log transformation. Definition of covariance. Nov 20: Using the ± sign to represent a confidence interval. See the example. Sept 12: How to calculate confidence limits from a p value, and a downloadable spreadsheet to do it. June 15: Updated Proc Mixed and added individual differences, and covariates. June 14: Plain-language definitions of confidence interval and statistical significance. May 11: Using proc mixed in SAS for repeated measures. Mar 29: Swapped axes in validity figure. (Silly mistake!) Mar 12: Note about checking the fit of non-linear models. Mar 8: Major revision of validity to give equal emphasis to systematic offset, standard deviation of the estimate, and validity correlation. Mar 8: Figure to show why not to use SEMs. Feb 19: Warning about specifying complex covariance structures with multiple crossovers. Jan 15: Reliability completely revised to give equal emphasis to shift in the mean, within-subject variation, and retest correlation. Minor changes to related pages. Spreadsheet for confidence intervals for reliability also now available. 1997 Nov 28: Latin squares to assign subjects in multiple crossovers. Nov 18: Multiple crossovers for experiments with several treatments. Nov 17: A small change in the way of representing the subject effect in repeated-measures models. Sept 8: How to analyze crossovers to account for any learning effect. Sept 7: Random vs fixed effects explained. Sept 5: Better explanations for calculating estimates and contrasts in various models. 12 June: Multiple linear regression improved. 10 June: Substantial revision of a scale of magnitudes for effect statistics. 06 June: Reworked sample size for complex cross-sectional studies. 05 June: Made p values and type II errors more understandable. 04 June: Sample size with more than one independent variable. 02 June: Major additions to Sample Size "On The Fly", including simulation programs. 28 May: Sample-size formula corrected to 2N(1 - r). 14 May: Sample-size estimation expanded. 13 May: Bootstrapping expanded. 13 May: Argument against adjusting confidence intervals and p values when reporting several effects. 12 May: First public release at Sportscience site.10 May: r=0.1 as a small
effect, in terms of change in X => change
in Y.10 May: Need to view SDs to decide whether to transform data: argument added to Mean ± SD or Mean ± SEM? 09 May: Argument against the notion of testing contrasts only if main effect is significant. 07 May: Release to acsmstats group. 01 May: First release to colleagues. |