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Randomized Controlled Trial
. 2016 Apr;42(2):162.
doi: 10.1590/S1806-37562016000000114.

What is the importance of calculating sample size?

[Article in English, Portuguese]
Cecilia Maria Patino  1 , Juliana Carvalho Ferreira  1
Affiliations
Randomized Controlled Trial

What is the importance of calculating sample size?

[Article in English, Portuguese]
Cecilia Maria Patino et al. J Bras Pneumol. 2016 Apr.
No abstract available

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Figures

Figure 1.
Figure 1.. Relationship between the size of the treatment effect and the estimated sample size. On the x axis, we show hypothetical values for the size of the treatment effect, expressed as scores on the asthma symptoms questionnaire. We considered a fixed degree of variability (standard deviation) of 0.5 points and a level of significance of 5%. As the size of the treatment effect increases, the estimated size of the sample decreases. It is also clear that for the same effect size, choosing a higher power to detect the effect of the treatment causes an increase in the sample size.
See this image and copyright information in PMC

References

    1. Zairina E, Abramson MJ, McDonald CF, Li J, Dharmasiri T, Stewart K. Telehealth to improve asthma control in pregnancy: a randomized controlled trial. Respirology. 2016 - PubMed
    1. Hulley SB, Cummings SR, Browner WS, Grady DG. Delineando a Pesquisa Clínica. 3. Porto Alegre: Artmed; 2008.
    1. Ferreira JC, Patino CM. What does the p value really mean. J Bras Pneumol. 2015;41(5):485–485. doi: 10.1590/S1806-37132015000000215. - DOI - PMC - PubMed

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