FAQ: How does this work?
To get your "performance index," the world record for the event is divided by your time. To find an equivalent performance, divide the world record by your performance index.
Easy example: Suppose that you are male and you run a 4:08 marathon. The world record for the men's marathon is 2:04, so your performance index would be 2:04/4:08 = 0.5. To find an equivalent performance in the men's road 5k, divide the men's road 5k world record of 13:00 by your performance index of 0.5: 13:00/0.5 = 26:00.
Hard example: I just ran 10:07.56 for the women's indoor 3k. So I divide the women's indoor 3k world record of 8:23.72 by my time: 8:23.72/10:07.56 = 0.829. Now I want to know what an equivalent performance in the indoor mile is, so I divide the women's indoor mile record of 4:17.14 by my performance index: 4:17.14/0.829 = 5:10.2.
FAQ: Can I use this to predict future performances?
You can, and I do. However, a better question is whether it is accurate in its predictions. You can use it to predict your mile time from your 3k time, but not your marathon time from your 3k time. Also, if the world record in a particular event was set while the runner was using performance-enhancing drugs, it will predict a faster-than-warranted finishing time in that event, and will similarly give you a lower-than-warranted performance index.*
Outside resources for predicting race times based on previous race times:
- Team Oregon has a chart of equivalent performances, and a pace wizard that you can use with your own times.
- The very detailed IAAF scoring tables, indoor (PDF) and outdoor (PDF).
- The Letsrun conversion table.
* I am personally recognizing the following marks as the valid women's world records:
Mile o-4:16.71 i-4:20.5
These times are not recognized as world records by the IAAF because someone on performance-enhancing drugs ran faster.
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