e-Articles (Chapter 8)

Here are some full-length research articles that illustrate a concern for effect size and power, application of the Bonferroni adjustment technique, and the use of confidence intervals to do hypothesis testing. To view any article, simply click on its title. (NOTE: No claim is made that these articles are perfect in all respects. By carefully reviewing them, you will hone your skills at being able both to decipher and to critique statistically-based research reports.)

How Accurate Is Patients' Anatomical Knowledge: A Cross-Sectional, Questionnaire Study of Six Patient Groups and a General Public Sample

In this study, an a priori power analysis was conducted to determine the sample sizes. See the 2nd paragraph of the "Methods" section, especially the last sentence in that paragraph.

Effects of Muscle Fatigue on Gait Characteristics Under Single and Dual-Task Conditions in Young and Older Adults

Illustrates the use of f and partial eta squared as estimates of effect size. See the 6th and 7th sentences of the "Statistical analysis" section, as well as the portions of the "Results" dealing with "Gait analysis" and the "Cognitive interference task."

The Effectiveness and Cost-Effectiveness of a Participative Community Singing Programme as a Health Promotion Initiative for Older People: Protocol for a Randomised Controlled Trial

In this description of a planned study, the researchers explain in detail how their needed sample size, for each of 2 comparison groups, was determined by (a) an a priori power analysis and (b) considering likely drop-out and consent rates. See the section in the "Methods" section called "Sample size."

Pharmacy Studentsí Participation in a Research Experience Culminating in Journal Publication

Illustrates the use of a confidence interval to do hypothesis testing. See the 2nd sentence in the "Results" portion of the "Abstract" and the 1st 3 sentences of the next-to-last paragraph of the article's main "Results" section. (Notice that the CI does not overlap 0.)

The Ontario Mother and Infant Study (TOMIS) III: A Multi-Site Cohort Study of the Impact of Delivery Method on Health, Service Use, and Costs of Care in the First Postpartum Year

In this published description of a planned study, the researchers discuss (a) the a priori power analysis they conducted to determine the needed sample size, (b) their planned use of the Bonferroni adjustment procedure "to keep the overall alpha level at alpha =.05," and (c) their intention to place a 95% confidence interval around the difference between 2 groups in terms of the percentage of women who experience postpartum depression. The description of the power analysis is nothing short of outstanding; see the 1st paragraph of the section called "Sample Size Calculation."

If you have seen or authored a research report that you think might help others understand power, effect size, Bonferroni, or the use of confidence intervals to do hypothesis testing, please contact me (shuck@utk.edu) and provide a link to what you have found or written. If I post the link on this page of my website, I promise to give you appropriate credit for first seeing/writing the item you share.

Copyright © 2012

Schuyler W. Huck
All rights reserved.

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