Calculating and reporting effect sizes on scientific papers (1): p < 0.05 limitations in the analysis of mean differences of two groups

Detalhes bibliográficos
Autor(a) principal: Espirito Santo, Helena
Data de Publicação: 2015
Outros Autores: Daniel, Fernanda Bento
Tipo de documento: Artigo
Idioma: por
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: https://doi.org/10.7342/ismt.rpics.2015.1.1.14
Resumo: The Portuguese Journal of Behavioral and Social Research requires authors to follow the recommendations of the Publication Manual of the American Psychological Association (APA, 2010) in the presentation of statistical information. One of the APA recommendations is that effect sizes should be presented along with levels of statistical significance.&nbsp;Since p-values from the results of the statistical tests do not indicate the magnitude or importance of a difference, then effect sizes (ES) should be reported. In fact, ES gives meaning to statistical tests; emphasizes the power of statistical tests; reduces the risk of interpreting mere sampling variation as real relationship; can increase the reporting of “non-significant" results, and allows the accumulation of knowledge from several studies using meta-analysis.&nbsp;Thus, the objectives of this paper are to present the limits of the significance level; describe the foundations of presentation of ES of statistical tests to analyze differences between two groups; present the formulas to calculate directly ES, providing examples of our own previous studies; show how to calculate confidence intervals; provide the conversion formulas for the review of the literature; indicate how to interpret the ES; and show that, although interpretable, the meaning (small, medium or large effect for an arbitrary metric) could be inaccurate, requiring that interpretation should be made in the context of the research area and in the context of real-world variables.
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spelling Calculating and reporting effect sizes on scientific papers (1): p < 0.05 limitations in the analysis of mean differences of two groupsCalcular e apresentar tamanhos do efeito em trabalhos científicos (1): As limitações do p < 0,05 na análise de diferenças de médias de dois gruposTamanho do efeitoSignificância estatísticaValor pd de Coheng de HedgesDelta de GlassEffect sizeStatistical significanceCohen's dp-valueHedges’ gGlass’s DeltaThe Portuguese Journal of Behavioral and Social Research requires authors to follow the recommendations of the Publication Manual of the American Psychological Association (APA, 2010) in the presentation of statistical information. One of the APA recommendations is that effect sizes should be presented along with levels of statistical significance.&nbsp;Since p-values from the results of the statistical tests do not indicate the magnitude or importance of a difference, then effect sizes (ES) should be reported. In fact, ES gives meaning to statistical tests; emphasizes the power of statistical tests; reduces the risk of interpreting mere sampling variation as real relationship; can increase the reporting of “non-significant" results, and allows the accumulation of knowledge from several studies using meta-analysis.&nbsp;Thus, the objectives of this paper are to present the limits of the significance level; describe the foundations of presentation of ES of statistical tests to analyze differences between two groups; present the formulas to calculate directly ES, providing examples of our own previous studies; show how to calculate confidence intervals; provide the conversion formulas for the review of the literature; indicate how to interpret the ES; and show that, although interpretable, the meaning (small, medium or large effect for an arbitrary metric) could be inaccurate, requiring that interpretation should be made in the context of the research area and in the context of real-world variables.A Revista Portuguesa de Investigação Comportamental e Social exige que os autores sigam as recomendações do Publication Manual of the American Psychological Association (APA, 2010) na apresentação da informação estatística. Uma das recomendações da APA é de que os tamanhos do efeito sejam apresentados associados aos níveis de significância estatística.&nbsp;Uma vez que os valores de p decorrentes dos resultados dos testes estatísticos não informam sobre a magnitude ou importância de uma diferença, devem então reportar-se os tamanhos do efeito (TDE). De facto, os TDE dão significado aos testes estatísticos, enfatizam o poder dos testes estatísticos, reduzem o risco de a mera variação amostral ser interpretada como relação real, podem aumentar o relato de resultados “não-significativos” e permitem acumular conhecimento de vários estudos usando a meta-análise.&nbsp;Assim, os objetivos deste artigo são os de apresentar os limites do nível de significância; descrever os fundamentos da apresentação dos TDE dos testes estatísticos para análise de diferenças entre dois grupos; apresentar as fórmulas para calcular os TDE, fornecendo exemplos de estudos nossos; apresentar procedimentos de cálculo dos intervalos de confiança; fornecer as fórmulas de conversão para revisão da literatura; indicar como interpretar os TDE; e ainda mostrar que, apesar de frequentemente ser interpretável, o significado (efeito pequeno, médio ou grande para uma métrica arbitrária) pode ser impreciso, havendo necessidade de ser interpretado no contexto da área de investigação e de variáveis do mundo real. &nbsp;Departamento de Investigação & Desenvolvimento do Instituto Superior Miguel Torga2015-02-28info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfapplication/ziptext/htmlhttps://doi.org/10.7342/ismt.rpics.2015.1.1.14https://doi.org/10.7342/ismt.rpics.2015.1.1.14Portuguese Journal of Behavioral and Social Research; Vol. 1 No. 1 (2015): February; 3–16Revista Portuguesa de Investigação Comportamental e Social; Vol. 1 N.º 1 (2015): Fevereiro; 3–162183-4938reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAPporhttps://rpics.ismt.pt/index.php/ISMT/article/view/14https://rpics.ismt.pt/index.php/ISMT/article/view/14/9https://rpics.ismt.pt/index.php/ISMT/article/view/14/13https://rpics.ismt.pt/index.php/ISMT/article/view/14/htmlDireitos de Autor (c) 2015 Helena Espirito Santo, & Fernanda Bento Danielhttp://creativecommons.org/licenses/by-nc/4.0info:eu-repo/semantics/openAccessEspirito Santo, HelenaDaniel, Fernanda Bento2023-05-25T22:00:43Zoai:ojs.rpics.ismt.pt:article/14Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T16:39:42.506959Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Calculating and reporting effect sizes on scientific papers (1): p < 0.05 limitations in the analysis of mean differences of two groups
Calcular e apresentar tamanhos do efeito em trabalhos científicos (1): As limitações do p < 0,05 na análise de diferenças de médias de dois grupos
title Calculating and reporting effect sizes on scientific papers (1): p < 0.05 limitations in the analysis of mean differences of two groups
spellingShingle Calculating and reporting effect sizes on scientific papers (1): p < 0.05 limitations in the analysis of mean differences of two groups
Espirito Santo, Helena
Tamanho do efeito
Significância estatística
Valor p
d de Cohen
g de Hedges
Delta de Glass
Effect size
Statistical significance
Cohen's d
p-value
Hedges’ g
Glass’s Delta
title_short Calculating and reporting effect sizes on scientific papers (1): p < 0.05 limitations in the analysis of mean differences of two groups
title_full Calculating and reporting effect sizes on scientific papers (1): p < 0.05 limitations in the analysis of mean differences of two groups
title_fullStr Calculating and reporting effect sizes on scientific papers (1): p < 0.05 limitations in the analysis of mean differences of two groups
title_full_unstemmed Calculating and reporting effect sizes on scientific papers (1): p < 0.05 limitations in the analysis of mean differences of two groups
title_sort Calculating and reporting effect sizes on scientific papers (1): p < 0.05 limitations in the analysis of mean differences of two groups
author Espirito Santo, Helena
author_facet Espirito Santo, Helena
Daniel, Fernanda Bento
author_role author
author2 Daniel, Fernanda Bento
author2_role author
dc.contributor.author.fl_str_mv Espirito Santo, Helena
Daniel, Fernanda Bento
dc.subject.por.fl_str_mv Tamanho do efeito
Significância estatística
Valor p
d de Cohen
g de Hedges
Delta de Glass
Effect size
Statistical significance
Cohen's d
p-value
Hedges’ g
Glass’s Delta
topic Tamanho do efeito
Significância estatística
Valor p
d de Cohen
g de Hedges
Delta de Glass
Effect size
Statistical significance
Cohen's d
p-value
Hedges’ g
Glass’s Delta
description The Portuguese Journal of Behavioral and Social Research requires authors to follow the recommendations of the Publication Manual of the American Psychological Association (APA, 2010) in the presentation of statistical information. One of the APA recommendations is that effect sizes should be presented along with levels of statistical significance.&nbsp;Since p-values from the results of the statistical tests do not indicate the magnitude or importance of a difference, then effect sizes (ES) should be reported. In fact, ES gives meaning to statistical tests; emphasizes the power of statistical tests; reduces the risk of interpreting mere sampling variation as real relationship; can increase the reporting of “non-significant" results, and allows the accumulation of knowledge from several studies using meta-analysis.&nbsp;Thus, the objectives of this paper are to present the limits of the significance level; describe the foundations of presentation of ES of statistical tests to analyze differences between two groups; present the formulas to calculate directly ES, providing examples of our own previous studies; show how to calculate confidence intervals; provide the conversion formulas for the review of the literature; indicate how to interpret the ES; and show that, although interpretable, the meaning (small, medium or large effect for an arbitrary metric) could be inaccurate, requiring that interpretation should be made in the context of the research area and in the context of real-world variables.
publishDate 2015
dc.date.none.fl_str_mv 2015-02-28
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
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dc.identifier.uri.fl_str_mv https://doi.org/10.7342/ismt.rpics.2015.1.1.14
https://doi.org/10.7342/ismt.rpics.2015.1.1.14
url https://doi.org/10.7342/ismt.rpics.2015.1.1.14
dc.language.iso.fl_str_mv por
language por
dc.relation.none.fl_str_mv https://rpics.ismt.pt/index.php/ISMT/article/view/14
https://rpics.ismt.pt/index.php/ISMT/article/view/14/9
https://rpics.ismt.pt/index.php/ISMT/article/view/14/13
https://rpics.ismt.pt/index.php/ISMT/article/view/14/html
dc.rights.driver.fl_str_mv Direitos de Autor (c) 2015 Helena Espirito Santo, & Fernanda Bento Daniel
http://creativecommons.org/licenses/by-nc/4.0
info:eu-repo/semantics/openAccess
rights_invalid_str_mv Direitos de Autor (c) 2015 Helena Espirito Santo, & Fernanda Bento Daniel
http://creativecommons.org/licenses/by-nc/4.0
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
application/zip
text/html
dc.publisher.none.fl_str_mv Departamento de Investigação & Desenvolvimento do Instituto Superior Miguel Torga
publisher.none.fl_str_mv Departamento de Investigação & Desenvolvimento do Instituto Superior Miguel Torga
dc.source.none.fl_str_mv Portuguese Journal of Behavioral and Social Research; Vol. 1 No. 1 (2015): February; 3–16
Revista Portuguesa de Investigação Comportamental e Social; Vol. 1 N.º 1 (2015): Fevereiro; 3–16
2183-4938
reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
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