Notes : DATA DESCRIPTIVE

DATA DESCRIPTIVE

 UNGROUPED DATA  

 MEAN  : Sum of all data / Number of data

 MEDIAN  :
1. Arrange data in order 
2. Choose middle point
3. Use the formula :

   



N = number of data

Example : 

Find the median of the set of data given : 

2.71, 3.56, 4.35, 5.48, 6.22, 8.61

Median = ( (6+1) / 2)th  
             = 3.5th observation
             
2.71, 3.56, 4.35,* 5.48, 6.22, 8.61

             = 1/2 ( 3th + 4th ) 
            = 1/2 ( 4.35 + 5.48 )
            = 4.915

RANGE : Highest data - Lowest data

QUARTILE : 



INTERQUARTILE RANGE  : Q3 - Q1   

Example : 

What is the interquartile range for the set of data?

20 , 30 , 40 *, 50 , ** 60 , 70 ,*** 80 , 90 

* Q1
** Q2
*** Q3

Therefore, interquartile range = ( 70 + 80 ) - ( 40 + 50 )
                                                = 150 - 90
                                                = 60

 GROUPED DATA 

 CLASSES OF DATA  : 

- 0, 10, 20, 30, 40, 50 are LOWER CLASS 

- 9, 19, 29, 39, 49, 59 are UPPER CLASS 

FREQUENCY DENSITY : Frequency / Class Width 

CLASS MARK : Midpoint ( ( Upper class- Lower class ) / 2 )

MODE :

MEDIAN : 

m = median
L = lower class of median
N = number of data
F = frequency before class median
fm = frequency of class median
c = breadth of class


QUARTILE :

 N = number of data
Q1 = lower/first quartile
Q3 = upper/third quartile

F = frequency before class median
fQ = frequency of class median
C = breadth of class

VARIENCE :

STANDARD DEVIATION : 

SUMMARY :