Thanks for visiting NZMaths.
We are preparing to close this site by the end of August 2024. Maths content is still being migrated onto Tāhūrangi, and we will be progressively making enhancements to Tāhūrangi to improve the findability and presentation of content.
For more information visit https://tahurangi.education.govt.nz/updates-to-nzmaths
A method used to smooth time-series data. It forms a new smoothed series in which the irregular component is reduced.
If the time series has a seasonal component a moving average is used to eliminate the seasonal component.
Each value in the time series is replaced by an average of the value and a number of neighbouring values. The number of values used to calculate a moving average depends on the type of time-series data. For weekly data, seven values are used; for monthly data, 12 values are used; and for quarterly data, four values are used. If the number of values used is even, the moving average must be centred by taking a two-term moving average of the new series.
In terms of an additive model for time-series data, Y = T + S + C + I, where
T represents the trend component,
S represents the seasonal component,
C represents the cyclical component, and
I represents the irregular component;
the smoothed series = T + C.
See: centred moving average, moving mean
Curriculum achievement objectives reference
Statistical investigation: (Level 8)
