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Form 1 Geography Online Lessons on Statistics
In this Lesson we are going to learn about the Data analysis techniques including: calculation of percentages and the measures of central tendency
(5m 33s)
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Answer Text:
Analysis of Data
Examining the numerical figures in detail.
Techniques of analysing Data
1. Calculation of Percentages
If in the study of a farm 10 hectares are devoted to coffee, what is the % of the area under coffee? 10/100×10%
The table below shows the number of tourists who visited Kenya from various parts of the world in 2006.
a) Calculate percentage increase of tourists from Africa between 2005 and 2006.
2. Measures of Central Tendency
 Outstanding general characteristics of the data.
a) Arithmetic Mean
 The average Advantages
• Easy to calculate for a small data
• Summarizes data using a single digit
• Easy to understand and interpret
Disadvantages
• Difficult to calculate for grouped data
• Affected by extreme values
b) Median
 The middle value in a set of data arranged in order.
M= (N+1)/2
(I) 20, 50, 90, 100, 150, 180, 200, 220, 240, 300, 360.
(II) 20, 50, 90, 100, 150, 180, 200, 220, 240, 300.
Advantages
• Easy to calculate in a small data set
• Easy to understand as it’s the value at the middle
Disadvantages
• Difficult to calculate in a large data set
• Doesn’t show data distribution
b) Calculation of Ranges
Difference between the largest and smallest values.
Calculate the range of for the data above.
c) Mode
 Most frequently recurring value in a set of data. 10, 2, 5, 9, 10, 11, 20, 15, 18, 10. The mode is 10.
Advantages
• Easy to find as no calculation is involved
• Easy to understand
Disadvantage
• Rarely used as a measure of central tendency
