Trend/Line Graphs A trend graph is a simple way of showing change over time. It can be used to show one set of information (variable), or several sets of information. All data is shown on one graph, meaning it can be easily compared.
How to Draw a Trend Graph
• Make sure that the units on the vertical y-axis are drawn to scale and named.
• Make that the horizontal x-axis is divided equally and named
(it does not need to be drawn to scale).
• Mark on each point and then join up the lines.
• Label each line and make each one a different colour. Climographs Valencia weather station 2015 No. of days with precipitation Average monthly temperature °C
10 12 14 16
0 2 4 6 8
Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Month
: Fig. 18.8 A climograph
Climographs combine a bar chart and a line graph to show the monthly precipitation and temperature for a certain area over a certain time. The bar graph shows precipitation, while the line graph depicts temperature. Each vertical axis has a different scale: the left represents precipitation and right represents temperature. These graphs also allow us to work out means and ranges.
ACTIVE LEARNING
Use Fig. 18.8 to answer the following questions.
1. What is the mean number of days per month when precipitation occurred?
2. Which months were the warmest? GEOGRAPHICAL SKILLS 311
3. Which months were the wettest? 4. What is the temperature range?
5. How many dry days were there that year?
10 11 12 13 14 15 16 17 18 19
6 7 8 9
0 1 2 3 4 5
ACTIVE LEARNING
1. Use Fig. 18.6 to answer the following questions:
(a) If the total frequency is 150, calculate the degrees in each segment.
(b) Calculate the number of students who travel to school by:
• Car • Bus
• Walking • Bicycle
2. Use Fig. 18.7 to answer the following questions:
(a) Which school had the largest enrolment increase between 2010 and 2011?
(b) In what year were two of the schools’ enrolments the same?
(c) In what year did school 3 have the largest enrolment?
(d) Which school had the largest average enrolment from 2010 to 2015?
(e) In what years did each of the schools have their largest enrolments?
GEO DICTIONARY Mean: the average
Range: the difference between the highest and lowest
