Rolling Average Movement Calculator
Smooth a run of daily movement rates into a rolling (moving) average to reveal the underlying trend beneath survey noise. Monitoring geotechs use it to decide whether a slope is genuinely speeding up or just showing scatter from refraction and single-reading error.
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How to use this calculator
- Enter the last N daily movement rates in mm/day — up to seven.
- Leave unused boxes blank; the tool averages only the values you enter.
- Read the rolling average as the smoothed trend, and check the maximum single-day rate for the worst reading in the window.
How it works
A rolling average is the mean of the most recent N daily rates: Σrᵢ / N. Day-to-day prism readings scatter because of atmospheric refraction, instrument resolution and the occasional bad shot, so a single day's rate can mislead. Averaging over a window cancels much of that noise and leaves the real trend.
The tool also reports the maximum single-day rate in the window. Smoothing can hide a genuine spike, so the peak is kept visible: a rising rolling average together with a high single-day maximum is a stronger warning than either figure alone.
Worked example
A five-day window. Daily rates of 2, 3, 1, 4 and 2 mm/day sum to 12, so the 5-day rolling average is 12 / 5 = 2.4 mm/day. The maximum single-day rate is 4 mm/day — worth noting even though the smoothed trend sits at 2.4.
Common mistakes
- Averaging cumulative displacements instead of daily rates — every input must already be a rate (mm/day).
- Choosing too long a window, which over-smooths and delays detection of a real acceleration.
- Ignoring the single-day maximum because the average looks calm.
Frequently asked questions
Why use a rolling average for slope monitoring?
Individual survey readings are noisy. A rolling average filters random scatter (refraction, instrument error, bad shots) so you see the genuine movement trend rather than one anomalous reading.
How many readings should I include?
Enough to suppress noise but not so many that the average lags reality. Three-to-seven-day windows are common for daily prism data.
Does smoothing hide a sudden jump?
It can, which is why this tool also reports the maximum single-day rate. Watch the peak alongside the average so a real spike is not averaged away.
Can I average negative rates?
Yes. Negative daily rates (recovery) are included in the mean, and the maximum returns the largest value, so a mixed run is handled correctly.
Related tools
- Prism Movement Rate Calculator
- Cumulative Movement Calculator
- Prism Movement TARP Checker
- RQD Calculator
- Crack Displacement Calculator
- Piezometer Trend Calculator
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Tip: Enter any known values to calculate the remaining results.
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