The natural tendency for the stylus and therefore the arm to be deflected towards the centre of the record seems counter intuitive, but it is caused by the off-set angle of the headshell. This offset angle, combined with the correct amount of stylus overhang, is necessary to ensure that the tone arm has at least two points on the record where the tracking error is nil. The system works well because even at its highest point, the tracking error between null points is hardly audible. The only downside to this arrangement is the aforementioned tendency for the stylus to move towards the spindle, and to counteract this, an equal and opposite anti-skate force needs to be applied, otherwise the stylus will rest more heavily on the left hand groove of the record (as seen from the front). Without friction however, the inward forces would not act on the stylus and so it is very much dependent on the depth of the groove, and the speed of the record, as to how much anti-skate needs to be applied.
 
Normally the best way to set the anti-skate is to match it to the tracking weight of the cartridge. Most tone arm manufacturers have carefully calibrated their various anti-skate mechanisms to make this more or less correct in normal use on a modulated record groove. However it can sometimes prove useful to fine tune the anti-skate by ear using a two tone modulated test groove on a test record. The method involves listening on headphones for intermodulation distortion between the two tones (it sounds like a faint buzz) and this can usually be tuned out by adjusting the anti-skate. Another method is to simply adjust the anti-skate while looking at the cantilever head-on, as it tracks a normal modulated groove at one of the null points on the record – if it is permanently deflected one way or the other, adjust the anti-skate until it is straight.
 
Using a blank disc may at first seem to be a good idea and it is erroneously advocated by many but unfortunately it does not truly represent the real situation in which the stylus finds itself in the modulated groove. For one thing, the very tip of the stylus never actually touches the record surface in a normal record groove, as it is only the sides of the stylus which contact the groove walls; with the tip of the stylus suspended above the bottom of the groove. If the stylus ever hits the bottom of the groove, it would be lifted clear of the information in the side walls. However, this is exactly what a blank record does - the stylus is riding on its very tip which causes it to experience a very different situation when compared to when it is in proper contact with the modulated record groove. This can cause it to exhibit more or less bias than usual, depending on the softness of the vinyl and shape and nature of the stylus tip. This is accentuated with highly polished large contact area line contact styli, whereas a simple spherical stylus would be less affected as its contact patch is more or less the same all round.