Measures of Variability

MEASURES OF VARIABILITY:
The presentation on this topic using the power point is very good.
Variability, the reporter emphasized that it is a spread out of the data. How tied up the distribution.
The reporter started with his report by reviewing the Mean.
Absolute Variability
a.Absolute Range= highest score-lowest scoere
b. Total Range= highest score-lowest score. Then the result will be added by one.
c. Kelly Range= P90-P10
It is good here if the data given is arranged from the highest to the lowest.
Quartile Deviation is applied when N is less than 30. QD= Q3-Q1/2.
Quartile Deviation is getting the middlemost score. Quart means 4.
Q3=3n/4
Q1=N/4
Quartile Deviation from the group data. This is applicable if N is 30 or more. Here solve first the Q3.
Formula:
Q= L+C(3N/4-summation of cF<)
__________________________
                   (CF)
I was not able to cope with the explaination of the following:
1. Average deviation
2. Variance
3.Correction
4.Variance from group data
5.Class deviation
6. others
I was confused in the above mentioned topic, maybe because of the different formula. So tomorrow I will bring this to the attention of the reporter to review first before proceeding to the next topics.
"Wise man talk because they have something to say. Fools man talk because they have to say something." By Plato.