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