Evidence map›Paper›PMID 25592936›Full record

ArticleSocial science research2015

The power of a paired t-test with a covariate.

E C Hedberg, Stephanie Ayers

Abstract read
In one paragraph

Article in Social science research, 2015. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 17 papers.

0numbers the graph read from it
0cells of the map it votes in
17citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

17 citing papers in PubMed.

  1. Trust in expert versus lay comments in online articles about spanking and car seat safety.Journal of family psychology : JFP : journal of the Division of Family Psychology of the American Psychological Association (Division 43) · 2021
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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

2 authors.

E C HedbergArizona State University, Sanford School of Social and Family Dynamics, United States; NORC at the University of Chicago, United States. Electronic address: ehedberg@asu.edu.
Stephanie AyersArizona State University, Southwest Interdisciplinary Research Center, United States.

Funding

Wave IV Data CollectionP01HD031921 · NICHD · UNIV OF NORTH CAROLINA CHAPEL HILL · PI HARRIS, KATHLEEN MULLAN · 1994 to 2020
$86.1M
Urban American Indian Youth Substance Use: Ecodevelopmental Influences P20MD002316 · NIMHD · ARIZONA STATE UNIVERSITY-TEMPE CAMPUS · PI MARSIGLIA, FLAVIO FRANCISCO · 2007 to 2016
$13.3M
'keepin' It REAL in Mexico: An Adaptation and Multisite RCTR01DA038657 · NIDA · ARIZONA STATE UNIVERSITY-TEMPE CAMPUS · PI MARSIGLIA, FLAVIO FRANCISCO · 2015 to 2019
$3.0M
Drug Resistance Strategies: The Next GenerationR01DA014825 · NIDA · ARIZONA STATE UNIVERSITY-TEMPE CAMPUS · PI MARSIGLIA, FLAVIO FRANCISCO · 2001 to 2001
$301k
NICHD NIH HHS P01 HD031921NIDA NIH HHS R01 DA014825NIDA NIH HHS R01 DA038657NIMHD NIH HHS P20 MD002316
6 · The paper itself

Abstract

Many researchers employ the paired t-test to evaluate the mean difference between matched data points. Unfortunately, in many cases this test in inefficient. This paper reviews how to increase the precision of this test through using the mean centered independent variable x, which is familiar to researchers that use analysis of covariance (ANCOVA). We add to the literature by demonstrating how to employ these gains in efficiency as a factor for use in finding the statistical power of the test. The key parameters for this factor are the correlation between the two measures and the variance ratio of the dependent measure on the predictor. The paper then demonstrates how to compute the gains in efficiency a priori to amend the power computations for the traditional paired t-test. We include an example analysis from a recent intervention, Families Preparing the New Generation (Familias Preparando la Nueva Generación). Finally, we conclude with an analysis of extant data to derive reasonable parameter values.

Indexed as

Data Interpretation, StatisticalHumansModels, StatisticalRegression AnalysisStatistics as TopicPaired t-testsRegressionStatistical power

Identifiers

PMID25592936
PMCPMC4297322

What OpenQuestion holds

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Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.