## Compound/Cumulative/Divided Bar Graph

Major cash crops exported in Kenya in tonnes

CROP | 1990 | 1991 | 1992 | 1993 | 1994 |

COFFEE | 4500 | 5000 | 5200 | 6000 | 5900 |

TEA | 1300 | 1100 | 2500 | 2100 | 2200 |

MAIZE | 800 | 900 | 500 | 400 | 400 |

WHEAT | 600 | 500 | 600 | 700 | 500 |

### Steps

CROP | 1990 | CT | 1991 | CT | 1992 | CT | 1993 | CT | 1994 |

COFFEE | 4500 | 4500 | 5000 | 5000 | 5200 | 5200 | 6000 | 6000 | 5900 |

TEA | 1300 | 5800 | 1100 | 6100 | 2500 | 7700 | 2100 | 8100 | 2200 |

MAIZE | 800 | 6600 | 900 | 7000 | 500 | 8200 | 400 | 8500 | 400 |

WHEAT | 600 | 7200 | 500 | 7500 | 600 | 8800 | 700 | 9200 | 500 |

TOTAL | 7200 | 7500 | 8800 | 9200 | 9000 |

- Set cumulative totals for the data each year
- Draw vertical axis(Y) to represent dependent variable
- Draw horizontal axis(x) to represent independent variable
- Label both axis using suitable scale
- Plot the cumulative values for each year
- Use values for components to subdivide the cumulative bar
- The subdivisions are placed in descending order with the longest at the bottom(coffee)
- Shade each component differently
- Put title and key

### Advantages

- It’s easy to construct
- It has good visual impression
- There is easy comparison for the same component in different bars because of uniform shading
- Easy to interpret because bars are shaded differently
- Total value of the bar can be identified easily

### Disadvantages

- It doesn’t show the trend of components (change over time).
- Can’t be used to show many components as there is limited space upwards
- Tedious as there is a lot of calculation work involved.
- Not easy to trace individual contribution made by members of the same bar
- Poor choice of vertical scale causes exaggeration of bars length leading to wrong conclusions

### Analysis

- Coffee was the leading export earner in the five years.
- Tea was the second leading export earner.
- Wheat had the lowest export quantity.
- 1993 recorded the highest export quantity.
- 1990 recorded the lowest export quantity.

## Piechart/Divided Circles/Circle Charts

- A circle which has been subdivided into degrees used to represent statistical data where component values have been converted in degrees.

**Major countries producing commercial vehicles in the world in 000s**

USA | FRANCE | JAPAN | UK | GERMANY | RUSSIA |

1800 | 240 | 2050 | 400 | 240 | 750 |

**Steps**

- Convert components into degrees

USA^{1800}/_{5480}×360=118.2◦

FRANCE^{240}/_{5480}×360=15.8◦

JAPAN^{2050}/_{5480}×360=134.7◦

UK^{400}/_{5480}×360=26.3◦

GERMANY^{240}/_{5480}×360=15.8◦

RUSSIA^{750}/_{5480}×360=49.3◦ - Draw a circle of convenient size using a pair of compasses.
- From the centre of the circle mark out each calculated angle using a protractor.
- Shade the sectors differently and provide the key for various shadings.

### Advantages

- Gives a good/clear visual impression
- Easy to draw.
- Can be used to present varying types of data e.g. minerals, population, etc.
- Easy to read and interpret as segments are arranged in descending order and are also well shaded.
- Easy to compare individual segments.

### Disadvantages

- Difficult to interpret if segments are many.
- Tedious due to a lot of mathematical calculations and marking out of angles involved.
- Can’t be used to show trend/change over a certain period.
- Small quantities or decimals may not be easily represented.

### Analysis

- The main producer of commercial vehicles is Japan.
- The second largest producer is USA followed by Russia.
- The lowest producers were France and West Germany with.

## Proportional Circles

- This is use of circles of various sizes to represent different sets of statistical data.

**Table showing mineral production In Kenya from year 1998-2000**

MINERALS | QUANTITY IN TONNES | ||

1998 | 1999 | 2000 | |

Graphite | 200 | 490 | 930 |

Fluorspar | 30 | 255 | 450 |

Soda ash | 270 | 300 | 350 |

Diamond | 500 | 870 | 1270 |

TOTAL | 1000 | 1915 | 3000 |

### Steps

- Determining the radii of circles by finding the square roots of the totals

1998 √1000=31.62=32

1999 √1915=43.76=44

2000 √3000=54.77=55

- Scale:1cm represents 10 tonnes

1998=3.2 cm

1999=4.4 cm

2000=5.5 cm

- Using a pair of compasses draw circles of different radii representing mineral production in Kenya between 1998 and 2000.
- Convert component values into degrees

Component value/total value of data×360

1998: Graphite-200/1000×360=72◦

Fluorspar-30/1000×360=10.8◦

Soda ash-270/1000×360=97.2◦

Diamond-500/1000×360=180◦

1999: Graphite-490/1915×360=92.1◦

Fluorspar-255/1915×360=47.9◦

Soda ash`300/1915×360=56.4◦

Diamond-870/1915×360=163.6◦

2000: Graphite-930/3000×360=11.6◦

Fluorspar-450/3000×360=54◦

Soda ash-350/3000×360=42.1◦

Diamond-1270/3000×360=152.3◦

- On the proportional circle for each year use a protractor and mark out the angles
- Shade the segments and then provide a key.

### Advantages

- They give a good visual impression.
- Easy to compare various components.
- Simple to construct.
- Easy to interpret as segments are arranged in descending order.
- Can be used to present varying types of data.

### Disadvantages

- Tedious in calculation and measurement of angles
- Actual values represented by each component cant be known at a glance
- Difficult to accurately measure and draw sectors whose values are too small.
- Comparison can be difficult if the circles represent values which are almost equal.

### Analysis/Conclusions

- Diamond was leading in production.
- The second leading mineral in production was graphite.
- The mineral with the lowest production was fluorspar.

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