## Statistical Presentation, Analysis and Interpretation

Temperature and Rainfall for Thika

 Month J F M A M J J A S O N D Temp(◦c) 24 24 23 22 19 17 17 18 19 20 22 23 Rainfall(mm) 109 122 130 76 52 34 28 38 70 108 121 120

Analysis and Interpretation

• The month with heaviest rainfall is May.
• The month with lowest rainfall is July.
• The hottest month was January and February.
• The months with lowest temperature were June and July.

Crop Production in Kenya in the Years 2001 and 2002

 crop Amount in metric tonnes 2001 2002 Tea 300,000 500,000 Coffee 120,000 80,000 wheat 120,000 150,000 Maize 250,000 400,000

Value of export Crops from Kenya (ksh million)

 Crop 1997 1998 1999 2000 2001 Tea 24126 32971 33065 35150 34485 Coffee 16856 12817 12029 11707 7460 Horticulture 13752 14938 17641 21216 19846
• If the data has large figures e.g. 195262 plot in 1000s=195, 184,988=185.
• You can draw comparative/group/multiple line and bar graphs from the data.

## Comparative/Group/Multiple Line Graph • Simple to construct
• Suitable when comparing trends or movements
• Comparison of items is easy because the graphs are drawn using common axis
• It’s easy to read exact values from each graph

• Number of items which can be represented are limited
• Crossing of lines may make interpretation and comparison difficult and confusing.
• Total amount of variable can’t be established at a glance.

## Comparative Bar Graph

• Easy to construct
• Easy to read and interpret
• Easy to compare similar components within different bars.
• Gives a good impression of totality.
• Individual contribution made by each component is clearly seen.
• Differences in quantity of components are clearly seen.

• Doesn’t show trend of components over time.
• Not easy to compare components where bars are many
• Not suitable for many components. ## Divided Bars or Rectangles

Production of Sugarcane in 1000 tonnes of 5 major factories in Kenya

 Factory Production(ooo tonnes) Length in cm Sony 50 0.5 Nzoia 100 1 Chemilil 200 2 Muhoroni 250 2.5 Mumias 400 4 Total 1000 10

Reported Visitor Arrivals by Continent for the Year 2000

 Continent No. of visitors Length of strip (cm) Africa 153904 1.5 America 77271 0.8 Asia 58784 0.6 Europe 663906 6.6 Other 82672 0.8 Total 10.3

Look for a convenient scale say 1cm rep 100000 visitors

• Draw a divided rectangle 10 cm long to represent the data.

- It should have the following:

• Title
• Key
• Width of 2 cm

Analysis and Interpretation

- To get the meaning of

• Factory leading in sugar production is Mumias.
• The 2nd leading is Muhoroni.
• Factory with the lowest production of sugar is Sony.
• Calculation of %s.

• Easy to construct
• Easy to compare components because they are arranged in ascending or descending order.
• Takes less space than when the data is presented using graphs.
• Each component proportion to the total can easily be seen at a glance.

• Can’t be used for a large data.
• Only one unit of measurement can be used.
• Difficult to assess values of individual component
• The visual impression isn’t as good as pie charts.

### Exercise

1. Temperature and Rainfall for Kisumu
 Month J F M A M J J A S O N D Temp(◦c) 19 20 20 18 20 19 19 18 18 18 18 18 Rainfall(mm) 18 38 66 127 114 84 112 104 69 56 38 31

1. Draw a bar graph to represent rainfall figures.
2. Calculate the mean monthly temperature for the place.
3. Calculate the mean annual temperature range.
4. Calculate the annual rainfall totals.
2.
 Temp/Day Mon Tue Wed Thurs Fri Sat Sun Max ◦c 28 27 28 26 29 29 26 Min ◦c 18 18 20 16 22 21 19

1. Calculate the diurnal/daily temperature range for Tuesday.
2. Calculate the mean daily temperature for Sunday.
3. Suppose at 40 ◦c air can hold 60g/m3 of water vapour and the maximum vapour it can hold is 70g/m3. Calculate the relative humidity.
4. (a) Calculate the time at Lamu 70◦E when time at GWM is noon.
(b) Calculate the longitude of Watamu whose time is 6pm when time at GWM is 9am.
5. Students from a certain school obtained the following marks in their end of term geography examination.
74, 52, 48, 60, 48, 32, 80, 67 and 85.
Calculate the following:
1. Median
2. Mode
3. Mean
6. (a) Calculate the scale given that the ground distance is 200km while the distance on the map is 20cm.
(b) A student measured the length of a road on a map from point A to B and found it to be 3.6 cm. Use a scale of 1:50000 calculate the actual/ground distance in km.
7. Students intend to carry out field study of a forest around their school.
1. State two ways in which they’d prepare themselves.
2. State 2 objectives they’d have formulated for their study.
3. List two problems they’d have encountered in the field.
4. State two follow up activities they would have after the field study.