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# Physics/Physical experiment repetition

Question
Dear Sir,
I would to like to know how many times should the physical experiment be repeated, in order to confirm the results accuracy?

Hello Ali,

I don't know of a rule or formula for recommended number of retests. You need to get a feel for how repeatable your results are from the first several measurements you take. I expect that after a certain number of repeats you will have confidence that more repeats will not show significant difference. Look at this wikipedia page.
https://en.wikipedia.org/wiki/Accuracy_and_precision
Scroll down to the 2 red targets. Notice that this page uses the term precision where repeatability might be more common. Focus first on the right-hand target and notice that it shows good precision. More repeats would not be likely to show a significant difference from what these 4 shots show. In the case of the left-hand target, more repeats might get you a more representative average.

In the case of doing a physical experiment, I do not expect you know a desired result such as you do in the case of shooting at a target. Some experiments will likely have more variation from one time to the next, other experiments will likely have less variation.

I hope this helps,
Steve
Questioner's Rating
 Rating(1-10) Knowledgeability = 8 Clarity of Response = 9 Politeness = 10 Comment Thank you Mr Steve Johnson very much and i hop you are always well.

Physics

Volunteer

#### Steve Johnson

##### Expertise

I would be delighted to help with questions up through the first year of college Physics. Particularly Electricity, Electronics and Newtonian Mechanics (motion, acceleration etc.). I decline questions on relativity and Atomic Physics. I also could discuss the Space Shuttle and space flight in general.

##### Experience

I have a BS in Physics and an MS in Electrical Engineering. I am retired now. My professional career was in Electrical Engineering with considerable time spent working with accelerometers, gyroscopes and flight dynamics (Physics related topics) while working on the Space Shuttle. I gave formal classroom lessons to technical co-workers periodically over a several year period.

Education/Credentials
BS Physics, North Dakota State University
MS Electrical Engineering, North Dakota State University