How many volunteers are needed for project?
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BBiernacki
- Posts: 1
- Joined: Wed Sep 05, 2018 9:05 pm
- Occupation: Teacher
How many volunteers are needed for project?
If a student is gathering data that requires human or animals, how many volunteers or animals would you recommend to have a valid experiment?
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SciB
- Expert
- Posts: 2068
- Joined: Fri Feb 01, 2013 7:00 am
- Occupation: Retired molecular biologist, university researcher and teacher
- Project Question: I wish to join Scibuddies to be able to help students achieve the best science project possible and to understand the science behind it.
- Project Due Date: n/a
- Project Status: Not applicable
Re: How many volunteers are needed for project?
Hi and welcome to Scibuddies,
How large a sample size to use for an experiment is an important question but one for which there is no simple answer. The number of human subjects or mice needed depends on what is being measured, the dependent variable, and how large a difference you predict between the measured values in the experimental group compared to the controls. In general, the greater the difference in the experimental mean compared to the control mean, the fewer subjects needed to obtain statistically meaningful data.
It is hard to explain how to calculate sample size without getting into a lot of statistical jargon, and it really does depend on what is being measured. The method is called a power analysis and is a statistically based way of obtaining a reasonably accurate value for the number of volunteers needed for a study or the number of animals needed for an experiment. If you want a more complete explanation of how a scientist arrives at the number of subjects for an experiment, I suggest that you take a look at some of these sites and then do a search yourself to find out more:
https://www.theanalysisfactor.com/5-ste ... mple-size/
https://en.wikipedia.org/wiki/Sample_size_determination
http://www.statsoft.com/Textbook/Power-Analysis
https://www.youtube.com/watch?v=Hyi8JiDJaMU
I hope this helps. I'm not an expert on statistics but I know the basics. There are several online programs you can use to calculate sample sizes for different power levels, but first you have to learn what the terms mean and understand how they are determined. If you still have questions let us know and we'll try to explain so you can understand and then you can explain it to your students so that they will get it.
Good luck!
Sybee
How large a sample size to use for an experiment is an important question but one for which there is no simple answer. The number of human subjects or mice needed depends on what is being measured, the dependent variable, and how large a difference you predict between the measured values in the experimental group compared to the controls. In general, the greater the difference in the experimental mean compared to the control mean, the fewer subjects needed to obtain statistically meaningful data.
It is hard to explain how to calculate sample size without getting into a lot of statistical jargon, and it really does depend on what is being measured. The method is called a power analysis and is a statistically based way of obtaining a reasonably accurate value for the number of volunteers needed for a study or the number of animals needed for an experiment. If you want a more complete explanation of how a scientist arrives at the number of subjects for an experiment, I suggest that you take a look at some of these sites and then do a search yourself to find out more:
https://www.theanalysisfactor.com/5-ste ... mple-size/
https://en.wikipedia.org/wiki/Sample_size_determination
http://www.statsoft.com/Textbook/Power-Analysis
https://www.youtube.com/watch?v=Hyi8JiDJaMU
I hope this helps. I'm not an expert on statistics but I know the basics. There are several online programs you can use to calculate sample sizes for different power levels, but first you have to learn what the terms mean and understand how they are determined. If you still have questions let us know and we'll try to explain so you can understand and then you can explain it to your students so that they will get it.
Good luck!
Sybee