Station details:
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Code: HEA
Latitude:  51.35830
Longitude:   -1.26389
Elevation:   114.0
Depth: 
Name: Headley
Region: England,United Kingdom
Status: 

        
Arrival picks statistics
Travel Time Analysis
On the top graph every dot represents the median residual for one month of data. The green line is the overall median; the orange line shows the standard deviation (smad) based on the median absolute deviation (mad), whilst the red line shows twice the standard deviation (2 * smad).
The bottom graph shows the number of residuals for each month. The red columns show the number of residuals whose median (for that month) is outside two standard deviations from the overall median (2 * smad).
Red dots indicate a possible clock error.
 

Station comments:
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Checked against station bulletin
BB opened 1981

Data at the ISC for 14 years between 1988 and 2013.