Time Series and Moving Averages

Time series data is collected at regular intervals over time. Moving averages smooth out short-term fluctuations so you can identify the underlying trend. This is tested on all three Edexcel GCSE papers.

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Key Vocabulary

Term	Definition
Time series	A set of data collected at regular time intervals
Trend	The general direction of the data over time (upward, downward, or level)
Seasonal variation	A pattern that repeats at regular intervals (e.g. quarterly, monthly)
Moving average	The mean of a fixed number of consecutive data points, recalculated as you move along the series
n-point moving average	The average of n consecutive values

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Plotting a Time Series

A time series graph has:

• Time on the horizontal axis (e.g. months, quarters, years).
• The variable on the vertical axis (e.g. sales, temperature, visitors).
• Points joined with straight lines.

Worked Example: Ice cream sales (£000s) over 8 quarters.