Standard Deviation, Sample, Population

https://statistics.laerd.com/statistical-guides/measures-of-spread-standard-deviation.php

https://www.khanacademy.org/math/statistics-probability/summarizing-quantitative-data/variance-standard-deviation-sample/a/population-and-sample-standard-deviation-review

https://stats.stackexchange.com/questions/485326/confused-when-to-use-population-vs-sample-standard-deviation-in-engineering-test

https://www.thoughtco.com/population-vs-sample-standard-deviations-3126372

https://www.statology.org/population-vs-sample-standard-deviation/

https://www.youtube.com/watch?v=ifQV_Rsvqks