Time Series Graphs

 

What Is a Time Series Graph?

A time series graph shows how a quantity changes over time.

• It’s also known as a line graph.
• Used to represent continuous data.
• Ideal for spotting trends, patterns, or changes over time.

 

Examples of Time Series Data:

• Temperature measured every hour
• Sales recorded monthly
• Speed of a car every second
• Number of people visiting a park each day

 

How Do I Draw a Time Series Graph?

Step-by-Step:

1. Horizontal axis (x-axis) = time
2. Vertical axis (y-axis) = quantity (e.g. temperature, height, profit)
3. Plot points accurately for each time and value pair
4. Join the points with straight lines using a ruler
5. If there are two or more data sets, use different colours or line styles and include a key

 

Example

A fitness instructor records the number of people in an outdoor class every 10 minutes during a 1-hour session:

 

Time (min)	People in Class
0	4
10	6
20	9
30	9
40	7
50	5
60	4

 

Plot these points on a time series graph and join them with straight lines.

 

 

How Do I Interpret a Time Series Graph?

Look for these features:

• Upward slope ( / ) = increase
• Downward slope ( \ ) = decrease
• Flat/horizontal line = no change
• Steep slope = rapid change
• Spike or dip = sudden jump or drop

 

Examples

(a) When were the most people in the class?

• Look for the highest point.
• Max = 9 people at 20 and 30 minutes

(b) When did the number stay the same?

• Look for horizontal lines.
• From 20 to 30 minutes, the value was constant at 9

(c) Describe the overall trend:

• People increased at first, peaked at 20–30 min, then declined
• General pattern: 📈 then 📉