I have a presumably easy question for you, but I am a real newbie in statistics, so please be patient. I have a data set containing $N$ values that more or less follows a normal distribution. I need to select $N/10$ values among them, creating a subset with the same distribution. How can I do that? Do you have softwares to recommend? I usually use PSPP.
A sufficiently large random sample taken from your normally distributed population would give you a normal distribution. The larger the sample, the closer it will be to the original distribution.
Choice of sample size will depend on how close you want to get to your population distribution.
I've never used PSPP, but it should have a random sampling feature.
You could use the sample() function in R.