Station details:
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Code: HGH
Latitude:  51.63800
Longitude:   -2.80639
Elevation:   210.0
Depth: 
Name: Gray Hill
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.
Travel time residuals
 

Station comments:
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Checked against station bulletin
opened 1980

Data at the ISC for 23 years between 1990 and 2012.