@@learnandapply I need help 🙋🏻♀️🙆🏼♀️In Standard deviation!! There are tow formulas!?!? I mean one formula we (divided by n-1 ) And the other one we (divided only n ) How i know when to use those !?!
If you going to calculate the standard deviation for population, then you need to use the formula with sigma, and for sample, you need to use the formula with s.
Hello sir, I am having airborne dust concentrations data as PM10, PM2.5, PM 1 . These data was taken before and during dust producing work in a civil construction site. N=5 How can i compare these before and during operations data ? It seems that there is percent variation in dust concentrations in atmosphere between before and during operation data. e.g., PM 10 ( particle size less than 10 microns) is sharing 40% of total airborne dust, and PM 2.5 ( particle size less than 2. 5 micron) shares 10% of total airborne dust. During machine operation: PM 10 shares 60% and PM 2.5 10% only. It seems that PM 10 share is increased due to that machine operation? Which test is suitable for analysing these type similar data for discussion ? How to use statistics? Any comparison among these particle sizes? thank u.
