How to create a training sample?

Question

data mining

I have recently become interested in machine learning, please tell me what to read / look at on the topic of creating a training sample (preferably in Russian, but not necessary). Googling did not help, most likely due to poor competence. Interested in:
1. ways to create
2. how to determine the required volume
3. how to evaluate the quality of the sample
If you think that it would be nice to get acquainted with something that I did not indicate here, I will also be very grateful.

Answer 1

There is a very good course on machine learning from andrew ng, one of the founders of coursera. The course is very useful in its entirety, especially part 10, "Advice for Applying Machine Learning" (by the way, the necessary volume is discussed there), and this lecture is devoted to the problem of obtaining a training sample.