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Why we should use simpler models if the data allow this: relevance for ANOVA designs in experimental biology

BACKGROUND: Analysis of variance (ANOVA) is a common statistical technique in physiological research, and often one or more of the independent/predictor variables such as dose, time, or age, can be treated as a continuous, rather than a categorical variable during analysis – even if subjects were ra...

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Detalles Bibliográficos
Autor principal: Lazic, Stanley E
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2008
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2496911/
https://www.ncbi.nlm.nih.gov/pubmed/18644134
http://dx.doi.org/10.1186/1472-6793-8-16
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author Lazic, Stanley E
author_facet Lazic, Stanley E
author_sort Lazic, Stanley E
collection PubMed
description BACKGROUND: Analysis of variance (ANOVA) is a common statistical technique in physiological research, and often one or more of the independent/predictor variables such as dose, time, or age, can be treated as a continuous, rather than a categorical variable during analysis – even if subjects were randomly assigned to treatment groups. While this is not common, there are a number of advantages of such an approach, including greater statistical power due to increased precision, a simpler and more informative interpretation of the results, greater parsimony, and transformation of the predictor variable is possible. RESULTS: An example is given from an experiment where rats were randomly assigned to receive either 0, 60, 180, or 240 mg/L of fluoxetine in their drinking water, with performance on the forced swim test as the outcome measure. Dose was treated as either a categorical or continuous variable during analysis, with the latter analysis leading to a more powerful test (p = 0.021 vs. p = 0.159). This will be true in general, and the reasons for this are discussed. CONCLUSION: There are many advantages to treating variables as continuous numeric variables if the data allow this, and this should be employed more often in experimental biology. Failure to use the optimal analysis runs the risk of missing significant effects or relationships.
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spelling pubmed-24969112008-08-06 Why we should use simpler models if the data allow this: relevance for ANOVA designs in experimental biology Lazic, Stanley E BMC Physiol Methodology Article BACKGROUND: Analysis of variance (ANOVA) is a common statistical technique in physiological research, and often one or more of the independent/predictor variables such as dose, time, or age, can be treated as a continuous, rather than a categorical variable during analysis – even if subjects were randomly assigned to treatment groups. While this is not common, there are a number of advantages of such an approach, including greater statistical power due to increased precision, a simpler and more informative interpretation of the results, greater parsimony, and transformation of the predictor variable is possible. RESULTS: An example is given from an experiment where rats were randomly assigned to receive either 0, 60, 180, or 240 mg/L of fluoxetine in their drinking water, with performance on the forced swim test as the outcome measure. Dose was treated as either a categorical or continuous variable during analysis, with the latter analysis leading to a more powerful test (p = 0.021 vs. p = 0.159). This will be true in general, and the reasons for this are discussed. CONCLUSION: There are many advantages to treating variables as continuous numeric variables if the data allow this, and this should be employed more often in experimental biology. Failure to use the optimal analysis runs the risk of missing significant effects or relationships. BioMed Central 2008-07-21 /pmc/articles/PMC2496911/ /pubmed/18644134 http://dx.doi.org/10.1186/1472-6793-8-16 Text en Copyright © 2008 Lazic; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( (http://creativecommons.org/licenses/by/2.0) ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Methodology Article
Lazic, Stanley E
Why we should use simpler models if the data allow this: relevance for ANOVA designs in experimental biology
title Why we should use simpler models if the data allow this: relevance for ANOVA designs in experimental biology
title_full Why we should use simpler models if the data allow this: relevance for ANOVA designs in experimental biology
title_fullStr Why we should use simpler models if the data allow this: relevance for ANOVA designs in experimental biology
title_full_unstemmed Why we should use simpler models if the data allow this: relevance for ANOVA designs in experimental biology
title_short Why we should use simpler models if the data allow this: relevance for ANOVA designs in experimental biology
title_sort why we should use simpler models if the data allow this: relevance for anova designs in experimental biology
topic Methodology Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2496911/
https://www.ncbi.nlm.nih.gov/pubmed/18644134
http://dx.doi.org/10.1186/1472-6793-8-16
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