graphs and measures of central tendency

Graphs and Measures of Central Tendency

Prepared by: Bhakti JoshiDate: November 18, 2011

Type of Data

Roll No. Age

1 182 183 184 185 196 167 188 179 1810 18

UNIVARIATE

Type of Data Mobile Brands Boys Girls

Total Students

Nokia 6 3 9Samsung 1 2 3BB 6 4 10Iphone 2 1 3HTC 0 1 1Sony 1 0 1Total Brands 16 11 27

COMPLEX

Graphsy-axis

x-axis1 2 3 4 5 6 7 8 9 10

1 2

3

4

5 6

7

8

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1

-7

-6

-5

-4

-3

-2

-1

1st Quadrant2nd Quadrant

3rd Quadrant 4th Quadrant

(+ , +)(- , +)

(- , -) (+ , -)

(x , y)

Types of Graphs

• Lines• Histograms• Pie Charts

Ages of Students Across Roll Numbers

Source: Class Survey Conducted on November 11, 2011

Ages of Students Across Roll Numbers

• Students distributed around the age of 17?

• Students distributed around the age of 19?

• Which graph is visibly clear and why?

Mobile Brand Ownership Among Boys and Girls

Source: Class Survey Conducted on November 11, 2011

Mobile Brand Ownership Among Boys and Girls

Source: Class Survey Conducted on November 11, 2011

Mobile Brand Ownership Among Boys and Girls

• Which graph explicitly shows the total number of mobile brands owned by students?

• What are major differences in both the graphs in terms of :– Data presented– Interpretation

• What kind of questions can be answered by the graphs?

Market Share of Vehicles During FY11

Source: Society of Indian Automobile Manufacturers (SIAM)

Market Share of Vehicles During FY11

• Which type of vehicles in India have the least market share?

• If the total sales (in numbers) during FY11 was 15,513,156, how many passenger vehicles were sold?

• If the market share of commercial vehicles is expected to increase from 4.36% to 5% during FY12, while other vehicles’ shares remained the same what will be the expected total sales in FY12?

SENSEX - Movement on Daily Basis

Source: Bombay Stock Exchange (BSE) - www.bseindia.com

SENSEX - Movement on Daily Basis

• Identify the dates when the SENSEX peaked• What is the nature of the graph? Cyclical,

steady, or fluctuating?• During which time period were there limited

fluctuations?

Wholesale Price Index (WPI) – Monthly Data Series

Source: Ministry of Commerce, Office of Economic Adviser, Government of India (GoI) – eaindustry.nic.in

Wholesale Price Index (WPI) – Monthly Data Series

• What is WPI?• Is it increasing?• By what rate did WPI decline during Feb-11?• Which time period and by what rate was the

WPI the highest between Oct-10 and Oct-11?

Ogives

Ages

Frequency of Mobile Phones Owned

Cumulative Frequency

Percentage Cumulative Frequency

10 - 14 3 3 (3/30)*100=10%

15 - 19 2 3+2 = 5 (5/30)*100=16.67%

20 - 24 6 5+6=11 (11/30)*100= 36.67%

25 - 29 7 11+7=18 (18/30)*100=60%

30 - 34 5 18+5=23 (23/30)*100=76.67%

35 - 39 2 23+2=25 (25/30)*100= 83.33%

40 - 44 5 25+5=30 (30/30)*100=100%

Ogives (Contd…)OGIVE

Measures of Central Tendency

• Known as summary statistics• Description of numerical information• Analysis of information from the middle point

of a distribution and hence the term “Central Tendency”

• The starting point to analyse the spread of the data (Measure of Dispersion)

Frequency and Distribution Curve

Email: bhaktij@gmail.comWebsite: www.headscratchingnotes.net