1. ECONOMICS
SS2

2. SCHEME OF WORK FOR FIRST TERM
The concept of national income
international trade and balance of payment.
economic Integration.
petroleum and the Nigerian economy.
economic growth and economic development.

3. Basic Tools For Economic Analysis
Economics ss 2
Basic Tools For Economic Analysis

4. Measure of variation (Dispersion)
Measurement of dispersion is the degree to which numerical data spread around the average.

5. The most common measure of dispersion are:
The range
The mean deviation
The standard deviation
The variance

6. The Range
The range of a set of number is the difference between the highest and lowest number in a set.
Example : the range of the set 2,2,3,5,8,12,15
Range =highest score- lowest score
15-2=13

7. The Mean Deviation
This measures the dispersion around the arithmetic mean and is the sum of the arithmetic mean divided by the total numbers of times the value occur.

8. M.d= / N M.D = / f Where M.d= mean deviation = sigma or the sum of
X = the variable
X = the arithmetic mean
N( f)= number eg times the value occurs

9. Example: Find the mean deviation of the set of numbers 2,3,6,8,11
Solution:
X= x
X = =30 = 6 N

10. x
X- x
/ x- x / 2 -4 4 3 -3 6 8 11 5
/x-x/= 14
M.d= /x-x/
=14/5=2.5 N

11. Standard Deviation
This is a measure of the degree of variation of a frequency distribution about its arithmetic mean.
S.D = (X- X) 2 N

12. Example: 1
find the standard deviation of the following set of number 2,3,6,8,11 solution
x = x = =30/5 N 5

13. x
X- x
( x- x ) 2 -4 4 3 -3 6 8 11 5 2

14. 2
s.d= (x-x) N

15. s.d= / =
s.d=3.29
s.d=3.3

16. The variance
The variance of set of data is define as the square of the standard deviation .
V= s.d 2

17. Assignment:
calculate the standard deviation and variance of the following set of numbers 2,2,5,7,7,7,9,9,9,10,10,11,12,18.