You can find the anti-skating bias setting underneath the tonearm on the Alva TT.
This setting applies a degree of counter rotational torque to the tonearm neutralising the force of the arm moving towards the centre of the record and ensuring the stylus is centred in the groove.
Without the anti-skating bias, the incorrect pressure would be applied to the tonearm causing it to jump and skip across the record and the stylus would wear unevenly.
The anti-skating bias setting is variable depending on which cartridge is used on the turntable. For the factory fitted Cambridge Audio high output moving coil cartridge the tracking force needs to be set to two grams.
Please see the diagram below: