Statistical Thinking in Biomedical Research
Division of Biostatistics & Epidemiology
Department of Health Evaluation Sciences
University of Virginia School of Medicine
Rob Abbott, Viktor Bovbjerg, Mark Conaway, Frank Harrell

Office of Continuing Medical Education
Fall 2002

Slide: 1

Section 1: Introduction to Statistical Concepts ¾ Frank Harrell

Slide: 2

What Do Biostatistics & Epidemiology Offer?

Slide: 3


Slide: 4

Statistical Inference ¾ Examples

Slide: 5

Infinite Data Case

Slide: 6

Finite Dataset

Slide: 7

Steps Involved in Statistical Inference

Slide: 8

Study Design Issues

Slide: 9

Response Variables

Slide: 10

Types of Studies/Believability of Results

Slide: 11

Randomized Experiments

Slide: 12

External Validity of Study Findings

Slide: 13

Pitfalls in Analysis & Interpretation

Slide: 14

Descriptive Statistics

Slide: 15

Analysis of Paired Observations

Slide: 16

What's Wrong with Percent Change?

Slide: 17

Objective Method for Choosing Effect Measure

Slide: 18

Biostat / Epi Resources at UVa

Slide: 19

How to Collaborate with Statisticians & Epidemiologists?

Slide: 20

Collaboration Issues

Slide: 21

Education Opportunities at UVa


D. G. Altman and J. M. Bland. Absence of evidence is not evidence of absence. British Medical Journal, 311:485, 1995.

J. C. Bailar III and F. Mosteller. Medical Uses of Statistics. NEJM Books, Boston, second edition, 1995.

C. Begg, M. Cho, S. Eastwook, R. Horton, D. Moher, I. Olkin, and et al. Improving the quality of reporting of randomized controlled trials. The Consort statement. Journal of the American Medical Association, 276:63-39, 1996.

T. C. Chalmers, H. Smith, B. Blackburn, B. Silverman, B. Schroeder, D. Reitman, and A. Ambroz. A method for assessing the quality of a randomized control trial. Controlled Clinical Trials, 2:3-9, 1981.

T. J. Cole. Sympercents: symmetric percentage differences on the 100 loge scale simplify the presentation of log transformed data. Statistics in Medicine, 19:310-125, 2000.

CPMP Working Party. Biostatistical methodology in clinical trials in applications for marketing authorizations for medicinal products. Statistics in Medicine, 14:165-682, 1995.

P. C. Gøtzsche. Blinding during data analysis and writing of manuscripts. Controlled Clinical Trials, 17:28-93, 1996.

L. Kaiser. Adjusting for baseline: Change or percentage change? Statistics in Medicine, 8:118-190, 1989.

R. A. Kronmal. Spurious correlation and the fallacy of the ratio standard revisited. Journal of the Royal Statistical Society A, 156:37-92, 1993.

T. A. Lang and M. Secic. How to Report Statistics in Medicine: Annotated Guidelines for Authors, Editors, and Reviewers. American College of Physicians, Philadelphia, 1997.

J. S. Maritz. Models and the use of signed rank tests. Statistics in Medicine, 4:14-53, 1985.

L. Törnqvist, P. Vartia, and Y. O. Vartia. How should relative changes be measured? American Statistician, 39:4-6, 1985.

RCTs include crossover studies, which can be of excellent quality when there are no carryover effects or when carryover effects are understood well enough to be ``subtracted out''.
Because absolute risks of events vary with disease severity, dictating that risk differences must vary.
Because of regression to the mean, it may be impossible to make the measure of change truly independent of the initial value. A high initial value may be that way because of measurement error. The high value will cause the change to be less than it would have been had the initial value been measured without error. Plotting differences against averages rather than against initial values will help reduce the effect of regression to the mean.