I am working on an independent research project involving animal models. I am unsure how to deterine how many animals (rats) to use for the project. The rats will be injected with different solutions to examine the effect on a target. There is nothing in the literature about trying any of the solutions in rats. How do I determine the amount of rats to use?


closed as off-topic by Remi.b, David, AliceD Jul 8 '18 at 20:57

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    $\begingroup$ I might be wrong, but I don't believe we consider general stats questions to be on-topic here even though we allow questions on technique. What you are asking about is called a "power analysis" in statistics; to do a power analysis you do need to have some prior expectation or knowledge of the estimated magnitude of the effect and variability or at least what magnitude of effect would be 'interesting' to you. $\endgroup$ – Bryan Krause Jun 26 '18 at 20:03
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    $\begingroup$ I'm voting to close this question as off-topic because it is about statistics and not biology. As Bryan said, you are interested in power analysis, the type of analysis for which you will need to estimate (eventually just a gut feeling estimate) the effect size that you're expecting. $\endgroup$ – Remi.b Jun 26 '18 at 23:37
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    $\begingroup$ The topic pertains to biostatistics which is a valid tag. $\endgroup$ – Hypnos Stratagem Jun 27 '18 at 0:05
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    $\begingroup$ This paper should help ncbi.nlm.nih.gov/pmc/articles/PMC3826013 $\endgroup$ – John Jun 27 '18 at 0:12
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    $\begingroup$ @Remi.b this is a completely valid question for here many factors for this have little to do with statistics and a lot to do with the animals physiology. $\endgroup$ – John Jun 27 '18 at 0:14