Any good way for analogRead readings calibration?

Thanks for naming the median filtering technic, using this now for several devices running Espruino. Works fine for me with sampleCount = 21.

analogReadMedian = function(p, sampleCount) {
      var samples = Math.floor(sampleCount);
      var analogValues = new Array(samples);
      // read analog values into array
      i = samples;
      while(i--) analogValues[i] = analogRead(p);
      //sort array, smalest first and largest last
      analogValues.sort(function(a, b){return a-b;});
      // set median
      i = Math.floor(samples/2);
      if ( samples % 2 ){ //even
          median = (analogValues[i]+analogValues[i+1])/2;
      } else { // odd
          median = analogValues[i];
      }
      return median;
};