When I calculated STD using software for two different samples, I got confused as I got a higher STD for smaller-size sample. I expect the STD will become greater for larger sample, because you will have a larger spread.
Then I realized I've mixed up the population and sample again.
1. The standard deviation is a measurement of the "spread" of your data.
Then I realized I've mixed up the population and sample again.
1. The standard deviation is a measurement of the "spread" of your data.
The standard deviation does not become lower when the number of measurements grows.
Note that both mean and standard deviation are population properties.
2. The standard error of the mean is the standard deviation of your estimate of the mean.
The standard error of the mean (i.e., the precision of your estimate of the mean) does get smaller as sample size increases.
If you take more measurements, you are getting a more accurate picture of the spread, which means the as you increase your number of observations you will on average get more precise estimates from your sample for both the population mean and standard deviation.
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