The uniques league compares the performance of major DXpeditions by ranking them according to the number of different callsigns appearing in their logs. After the first one, any additonal QSOs with the same station do not add to the uniques count. Under this metric, DXpeditions that work lots of different people score higher than those that work the same people repeatedly on various bands and modes ('slot-fillers'). A greater proportion of their QSOs probably qualify as ATNO's (All-Time New Ones).
Some DXpeditions are specialist in nature. An IOTA DXpedition to Rockall, for example, is of little interest to anyone chasing DXCC, but may be highly sought after by fans of IOTA. Likewise, a 6m EME DXpedition to Micronesia will be a must-have for 6m moon-bouncers but essentially irrelevant to most HF DXers. The 'unique callsigns' metric takes no account of the different populations of hams who would actually want to contact the DXpeditions.
Other possible DXpedition metrics include:
- Total number of QSOs, with or without counting duplicates (however one defines a 'duplicate'). The QSO count is a simple, easy, relatively crude metric.
- QSOs per operator-day: this is an attempt to measure the productivity of the operators on the trip according to how many QSOs they make per day. For example, operators in a ten-man team that made a total of 100,000 QSOs made an average of 10,000 QSOs each. If the DXpedition was on the air for ten days, they made 1,000 QSOs per operator-day.
- Band-slots filled: this metric is similar to the total number of QSOs excluding duplicate QSOs on the same band and mode, but puts emphasis on contacting as many hams as possible on different modes and bands.
- $ per QSO: the high cost of mounting a major DXpedition to somewhere remote and inaccessible means that, in effect, each QSO they make typically costs a few dollars.
- QSOs per watt-hour is one way of measuring the energy efficiency of the operation. QRP or barefoot DXpeditions probably won't make as many QSOs as those using linear amplifiers, but may well score better on this kind of metric. This metric could also extend to measuring the fossil fuel burnt to get the team and equipment to/from the location, or the non-radio energy consumption on site, for cooking, heating, lighting etc.
- QSOs or unique callsigns worked per most-wanted-rank reflects the relative high worth of DXpeditions to highly-sought-after locations over those that operate from run-of-the-mill locations. A DXpedition that makes just 100 [valid, licensed, DXCC-claimable!] QSOs from North Korea may be judged better by the DX community as a whole, than one that made thousands of QSOs from the Marshall islands, for instance. For the 100 lucky people in the log, it probably rates as the most wonderful DXpedition ever!
The Club Log uniques league doesn't go into all these factors, but hopefully this page has given you some insight into the factors that get considered when planning "Where to next?"