Ok so when you start there is loads of new terminolgy and new formulas to learn one being standard deviation and one being variance these both aim to show you the spread of data or to put it in other words how close the data is grouped together. These both include another forumla which has a notation of Sxx (Sum of Squares). So before your can find out standard deviation you must first find the value of Sxx. The simple way to learn them is to first no that you only need to formulas to find out Sxx and that is because you need one for data in a frequency table and one for data that doesnt appear in a frequency table. The formula for Sxx in a table is Sxx=(Sum of) X^2-n(times)Mean^2
^ means to the power of. n= the number of data values.
The formula for the Sxx when its in a frequency table. Sxx=(Sum of) X^2(times)F-n(times)Mean^2.
F= the frequency.
Now you need to know the formula for standard deviation which has the notation of a little s. So s=(the square root of )Sxx/n-1.
/=divide. When square rooting make sure that you do Sxx/n-1 first.
variance is the same formula just not square rooted so has the rotation of s^2. so s^2=Sxx/n-1.
This is all you need to know about standard deviation and variance if you need more help with this comment or post on the forum
^ means to the power of. n= the number of data values.
The formula for the Sxx when its in a frequency table. Sxx=(Sum of) X^2(times)F-n(times)Mean^2.
F= the frequency.
Now you need to know the formula for standard deviation which has the notation of a little s. So s=(the square root of )Sxx/n-1.
/=divide. When square rooting make sure that you do Sxx/n-1 first.
variance is the same formula just not square rooted so has the rotation of s^2. so s^2=Sxx/n-1.
This is all you need to know about standard deviation and variance if you need more help with this comment or post on the forum