nl_tokens: Incorporate a speed sampling into the mean speed and ( running ) variance .
pl_tokens: function recordSpeed ( child , speed ) { child . runCount += sampleSize if ( passCount > 1 ) { var square = Math . pow ( speed - child . speed , 2 ) child . variance += ( square - child . variance ) / ( passCount - 1 ) } child . speed += ( speed - <mask> . speed ) / passCount }