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power, effect size and sample size - Coggle Diagram
power, effect size and sample size
prospective power analysis
to calculate minimum sample size
need to know: anticipated effect size desired power level
can use power tables, or power calculators
anticipated effect size
do we think the effect of our factor on the DV will be small medium or large
can make a guess by
looking at the research literature/similar studies
doing a smaller pilot study
deciding the smallest effect of interest
power analysis with power table
tables let you calculate power from planned sample size and anticipated effect size
gives a rough idea of sample size
what can effect statistical power
sample size
effect size
experimental design
bonferroni a level
power analysis with GPower
quicker and more accurate
to calculate need to know:
study design
anticipated effect size
a level
desired power level
prospective vs retrospective power analysis
ideally power analyses should always be done before starting a study
can also be done after a study is completed but its less useful
can be used to work out the power of the study if there weren't enough participants recruited
uses actual effect size and sample size to calculate achieved power
might help to explain a null finding