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3.5.1 Initial Felo ratings for the whole group

Estimating the initial Felo ratings for a fencing group is the only tricky part when using Felo. Fortunately, it has to be done only once. It is necessary because the Felo system can only calculate changes in the Felo rating, hence the initial value must come from somewhere else.

So, the starting point is a bunch of fencing Felo-virgins. Somebody of the group who is trustable must estimate everybody with preliminary initial values. This shouldn't be too critical since Felo will recalculate all numbers anyway; more or less, it is only about determining the mean fencing strength of the group.

I recommend to use the table in section Felo ratings as a guide, and to round all values to 100 points. Thus, a possible result could be:

     Alexander          1600
     Julia              1400
     Christian          1600
     Mike               1300
     Max                1500
     George             1500
     Peter              1700
     Christine          1400
     William            1700

The second important ingredient are bout results, the more the better, although they should not be spread over a too long period of time. Five to ten bouts per fencer are a soft minimum, having taken place within half a year. It's not a big deal if you don't fulfil these preconditions, though. You enter the bout results and do the so-called bootstrapping. It means that the Felo program calculates the best initial values from the preliminary ones provided by you.

For doing this, click on “Calculate” – “Bootstrapping”:

clicking on bootstrapping

Then you click on “Yes” and wait for a couple of seconds (at most). The new initial values are inserted into the file. You should save the file and you shouldn't touch the initial Felo ratings again, unless you know what you're doing. From now on, only bouts and new fencers are added to the file.

If you haven't recorded any bouts for far, you can use the preliminary initial values, too, however, you must expect some wild behaviour during the first weeks, until the Felo ratings have found their true values.

On the other hand, if you already have a lot of bouts data, you should use only the first part of it (e.g. the first six months) for the bootstrapping.