Examining the numerical figures in detail.
Techniques of analysing Data
- 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.
Measures of Central Tendency
Outstanding general characteristics of the data.
a) Arithmetic Mean
The average
Advantages
- Easy to calculate for a small data
- Summarises 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
- 20, 50, 90, 100, 150, 180, 200, 220, 240, 300, 360.
- 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
- Statistical Presentation of Data