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Assessing standardized contrast effects in ANCOVA: Confidence intervals, precision evaluations, and sample size requirements
Standardized effect sizes and confidence intervals are useful statistical assessments for comparing results across different studies when measurement units are not directly comparable. This paper aims to describe and compare confidence interval estimation methods for the standardized contrasts of tr...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Public Library of Science
2023
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9955653/ https://www.ncbi.nlm.nih.gov/pubmed/36827246 http://dx.doi.org/10.1371/journal.pone.0282161 |
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author | Shieh, Gwowen |
author_facet | Shieh, Gwowen |
author_sort | Shieh, Gwowen |
collection | PubMed |
description | Standardized effect sizes and confidence intervals are useful statistical assessments for comparing results across different studies when measurement units are not directly comparable. This paper aims to describe and compare confidence interval estimation methods for the standardized contrasts of treatment effects in ANCOVA designs. Sample size procedures are also presented to assure that the resulting confidence intervals yield informative estimation with adequate precision. Exact interval estimation approach has theoretical and empirical advantages in coverage probability and interval width over the approximate interval procedures. Numerical investigations of the existing method reveal that the omission of covariate variables has a negative impact on sample size calculations for precise interval estimation, especially when there is disparity in influential covariate variables. The proposed approaches and developed computer programs fully utilize covariate properties in interval estimation and provide accurate sample size determinations under the precision considerations of the expected interval width and the assurance probability of interval width. |
format | Online Article Text |
id | pubmed-9955653 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2023 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-99556532023-02-25 Assessing standardized contrast effects in ANCOVA: Confidence intervals, precision evaluations, and sample size requirements Shieh, Gwowen PLoS One Research Article Standardized effect sizes and confidence intervals are useful statistical assessments for comparing results across different studies when measurement units are not directly comparable. This paper aims to describe and compare confidence interval estimation methods for the standardized contrasts of treatment effects in ANCOVA designs. Sample size procedures are also presented to assure that the resulting confidence intervals yield informative estimation with adequate precision. Exact interval estimation approach has theoretical and empirical advantages in coverage probability and interval width over the approximate interval procedures. Numerical investigations of the existing method reveal that the omission of covariate variables has a negative impact on sample size calculations for precise interval estimation, especially when there is disparity in influential covariate variables. The proposed approaches and developed computer programs fully utilize covariate properties in interval estimation and provide accurate sample size determinations under the precision considerations of the expected interval width and the assurance probability of interval width. Public Library of Science 2023-02-24 /pmc/articles/PMC9955653/ /pubmed/36827246 http://dx.doi.org/10.1371/journal.pone.0282161 Text en © 2023 Gwowen Shieh https://creativecommons.org/licenses/by/4.0/This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
spellingShingle | Research Article Shieh, Gwowen Assessing standardized contrast effects in ANCOVA: Confidence intervals, precision evaluations, and sample size requirements |
title | Assessing standardized contrast effects in ANCOVA: Confidence intervals, precision evaluations, and sample size requirements |
title_full | Assessing standardized contrast effects in ANCOVA: Confidence intervals, precision evaluations, and sample size requirements |
title_fullStr | Assessing standardized contrast effects in ANCOVA: Confidence intervals, precision evaluations, and sample size requirements |
title_full_unstemmed | Assessing standardized contrast effects in ANCOVA: Confidence intervals, precision evaluations, and sample size requirements |
title_short | Assessing standardized contrast effects in ANCOVA: Confidence intervals, precision evaluations, and sample size requirements |
title_sort | assessing standardized contrast effects in ancova: confidence intervals, precision evaluations, and sample size requirements |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9955653/ https://www.ncbi.nlm.nih.gov/pubmed/36827246 http://dx.doi.org/10.1371/journal.pone.0282161 |
work_keys_str_mv | AT shiehgwowen assessingstandardizedcontrasteffectsinancovaconfidenceintervalsprecisionevaluationsandsamplesizerequirements |