For 1-way ANOVA in G*Power, you need to input the average standard deviation (SD) of the groups, NOT the sum of all SDs. This value represents the variability within each group and it is used as the basis for estimating the required sample size. You can estimate this average SD from previous research or pilot data, or by calculating it from a smaller sample of your current study. If you don't have any information about the SD, you can input a reasonable estimate or use a conservative value (e.g., the largest SD from previous research or pilot data) to ensure that your sample size calculation is robust.
please find this paper:
Statistical notes for clinical researchers: Sample size calculation 3. Comparison of several means using one-way ANOVA
Restor Dent Endod. 2016 Aug; 41(3): 231–234.
Published online 2016 Jul 26. doi: 10.5395/rde.2016.41.3.231
in short, there is an equation in the paper that you can use to calculate "SD σ within each group"
sorry I did not share the correct link. Here is the one:
J Educ Eval Health Prof. 2021; 18: 17.
Published online 2021 Jul 30. doi: 10.3352/jeehp.2021.18.17
PMCID: PMC8441096
PMID: 34325496
Sample size determination and power analysis using the G*Power software
Pinting Bian Can the calculation done there for 'spooled SD' be incorrect? shouldn't it be this-
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