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TASMathematics ApplicationsQuick questions
Unit 4
Quick questions on Time Series and Forecasting - TCE Mathematics Applications (Tasmania)
5short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What are smoothing with moving averages?Show answer
A moving average replaces each value with the average of itself and its neighbours, which smooths out short-term fluctuations and reveals the trend. The number of points averaged is the order. For an odd order (e.g. 3 or 5), the smoothed value lines up directly with a data point.
What are compute the smoothed values?Show answer
The smoothed series rises steadily, showing an upward trend once the day-to-day noise is removed. There is no smoothed value for the first or last day.
What are seasonal indices?Show answer
A seasonal index measures how a particular season compares with the average. An index of means that season runs above the average; means below. For data with seasons, the indices must add to (for example, four quarterly indices sum to , and average to ).
What is project the trend, then reseasonalise?Show answer
Reseasonalise: .
What is trend-line forecasting?Show answer
Once you have a trend line (often a least-squares line fitted to time on the horizontal axis), substitute the future time value to forecast. As with regression, forecasting far beyond the data is extrapolation and grows less reliable the further out you go.
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