Statistical Methods - Geography Form 2 Notes

• Statistical Presentation, Analysis and Interpretation
• Comparative/Group/Multiple Line Graph
• Comparative Bar Graph
• Divided Bars or Rectangles

Statistical Presentation, Analysis and Interpretation

Temperature and Rainfall for Thika

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

Value of export Crops from Kenya (ksh million)

• 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

Advantages

• 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

Disadvantages

• 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

Advantages

• 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.

Disadvantages

• 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

Reported Visitor Arrivals by Continent for the Year 2000

Look for a convenient scale say 1cm rep 100000 visitors

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

- It should have the following:

• Title
• Different shades
• Key
• Width of 2 cm

Analysis and Interpretation

- To get the meaning of

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

Advantages

• 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.

Disadvantages

• 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
   4. State their advantages and disadvantages.
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.