WRTC 2006 DXspot / Log analysis

Thanks to the policy of the WRTC 2006 to make all logs public and thus offering a data pool of about 85000 QSOs, it is possible to generate a lot of interesting statistics. One topic in contesting that has been discussed a lot lately is cheating by using the DX-Cluster but claiming unassisted.

By using the data from 46 WRTC log and the collected DX-Cluster spots for each of the WRTC-stations from the OH2AQ-Database, it is easy to draw conclusions who was using the DX-Cluster to find WRTC stations and who didn't.

Correlating Cluster Spots with Log Entries

This analysis bases on the assumption, that there is a correlation between the time at which a DX-spot is made and the time of the appearance of a station who saw the spot in the contest log. For every spot that shows up in the database for a certain station, say PT5V, the contents of the following x minutes of PT5V's log are evaluated, where the value of the time frame x can be varied.

Example

Right at the start of the contest, PT5V was spotted by NQ4I.

NQ4I      21012.7 PT5V                                      1212 08 Jul 2006

Lets say the time frame was set to 5 minutes. The following QSOs from PT5V's log are extracted:

QSO: 21012 CW 2006-07-08 1212 PT5V          599 15     NQ4I          599 08 
QSO: 21012 CW 2006-07-08 1212 PT5V          599 15     KA9FOX        599 07 
QSO: 21012 CW 2006-07-08 1212 PT5V          599 15     NO2R          599 08 
QSO: 21012 CW 2006-07-08 1213 PT5V          599 15     W5GN          599 07 
QSO: 21012 CW 2006-07-08 1213 PT5V          599 15     K3ND          599 08 
QSO: 21012 CW 2006-07-08 1213 PT5V          599 15     VA2WDQ        599 04 
QSO: 21012 CW 2006-07-08 1213 PT5V          599 15     W9IU          599 08 
QSO: 21012 CW 2006-07-08 1214 PT5V          599 15     W1ZT          599 08 
QSO: 21012 CW 2006-07-08 1214 PT5V          599 15     WA5POK        599 07 
QSO: 21012 CW 2006-07-08 1215 PT5V          599 15     K8MFO         599 08 
QSO: 21012 CW 2006-07-08 1215 PT5V          599 15     W9OL          599 08 
QSO: 21012 CW 2006-07-08 1215 PT5V          599 15     W3YY          599 08 
QSO: 21012 CW 2006-07-08 1215 PT5V          599 15     K2AAW         599 07 
QSO: 21012 CW 2006-07-08 1216 PT5V          599 15     WB2AA         599 08 
QSO: 21012 CW 2006-07-08 1216 PT5V          599 15     PX5A          599 15

For every callsign which appears in this time frame, except the callsign of the spotting station itself, a counter is increased. These stations have possibly used the DX-cluster spot, sent by NQ4I, to find and work PT5V, but this might just have been coincidence.

This will be repeated for every single DX-spot that has been sent during the WRTC. About 2650 spots for the PT5/PW5-stations have been made, which results in 2650 possible x-minute time frames. In every of these time frames, the number of appearances of every single callsign in the corresponding log was counted.

Evaluation

Just counting the absolute number of appearances after a DX-spot would not make much sense. A station that works 100 QSOs with WRTC stations and - by coincidence - 20 of these QSOs happen within x minutes after a DX-spot would look more suspicious than someone who works a total of 10 WRTC stations and 9 of them within a time frame after a spot.

What is interesting is the percentage of QSOs for a specific station that were made within x minutes after a DX-spot.

Since there are quite a number of uniques within the WRTC logs, and - by the rules of coincidence - many of them are within a time frame after a DX-spot, it makes sense to set a threshold for the minimum number of QSOs accross all WRTC logs, for a callsign to be included in the results. In the given results (see below), thresholds of 0, 10 and 20 were chosen.

Results

Here are the links to the results. The results with a threshold of 0 are just included for completeness probably not very helpful.

Time frame:2 minutes5 minutes10 minutes
Threshold (QSOs): (0) / 10 / 20 (0) / 10 / 20 (0) / 10 / 20

The first column of the tables contains the percentage of QSOs that a station made with any WRTC-Stations, that fell within a x minute time frame after a DX-spot.

The second column is the total number of QSOs that followed a DX-spot, the third column is the total number of QSOs with WRTC stations, fourth column is the callsign, followed by the claimed category and score of their log submission (if available).

Examples

The results speak for themselves, have a look and draw your conclusions. It seems that quite a number of stations that submitted as single OP might have used the DX-cluster to aid finding WRTC-stations...

To illustrate the effects of changing the time frame, lets have a look at two different callsigns, N3RS (Single OP) and NO2R (M/S).

NO2R claimed Multi-One and also submitted a lot of packet spots during the contest, so he was clearly using the DX-cluster. He made a total of 163 QSOs with WRTC stations during the contest. The following table shows, the distribution of his QSOs after spots, within a 2-, 5- and 10-minute time frame.

Time frame%QSOsincrease %
255.2900
571.211616
1080.41319.2

More than half of the WRTC stations were worked within 2 minutes after a spot for them, another strong increase by 16% to 71.2% is made within the 3 minutes until the 5 minute-window is over. In the following 5 minutes, until the 10-minute window is over, only a few more stations are worked.

The analysis of N3RS, who claimed single OP (unassisted) shows totally different picture. He made a total of 166 QSOs with WRTC stations. The following table shows the same data as the table for NO2R above.

Time frame%QSOsincrease %
219.9330
538.66418.7
1060.810122.2

Only one fifth of the spotted WRTC stations were worked within 2 minutes after a spot for them appeared. The increase with increasing time from the spot is remarkably higher, i.e. the longer the time difference between the spot, the higher the probability for a QSO. This result lets no doubt that N3RS was actually not using the DX-cluster (noone would have suspected anyway ;-), the correlation between his QSOs and the spots is significantly lower compared to NO2R.

Both N3RS and NO2R show a typical pattern for their respective categories. If you have a close look at the full results, you will find a lot of stations who absolutely do not fit into this pattern...

Finally...

There are several problems which are not covered by the methods to generate these simple statistics:

All raw data, the source code used to generate the statistics etc. is available here.

Any comments, critics etc appreciated via e-Mail mail@fkurz.net

Fabian, DJ1YFK
fkurz.net
Last modified: 12.06.2007 - 02:24