Sample Size, Power & Efficient design Flashcards
Statistical power definition
The probability of being able to correctly reject a hypothesis when the hypothesis is false
What is statistical power?
what % of 100 identical experiments will produce the same significant results
What 4 factors effect statistical power?
The effect size
Amount of natural variation in the experimental unit
ED & statistical test used
Number of independent replicates
What is the effect size what does it show
a quantitative measure of the magnitude of the experimental effect
larger effect size = stronger relationship between 2 variables
What is the amount of random variation in the experimental unit
the natural biological variation in a experimental unit (eg egg shell thickness)
^ variability = decreased statistical power
How does the number of independent replicates effect statistical power
^ independent replicates = ^ statistical power
How is variance & SD calculated?
Variance = averaged squared difference between each observation & group mean
SD = square root of variance
How is effect estimate calculated
mean of intervention group - mean of control group
What is a power analysis?
a computer simulation / use of statistical software to estimate the minimum sample size required for an experiment
