code: function normalci() {
      var args = slice.call(arguments),
      ans = new Array(2),
      change;
      if (args.length === 4) {
        change = Math.abs(jStat.normal.inv(args[1] / 2, 0, 1) *
                          args[2] / Math.sqrt(args[3]));
      } else {
        change = Math.abs(jStat.normal.inv(args[1] / 2, 0, 1) *
                          jStat.stdev(args[2]) / Math.sqrt(args[2].length));
      }
      ans[0] = args[0] - change;
      ans[1] = args[0] + change;
      return ans;
    }
docs: 2 different parameter setups (value, alpha, sd, n) (value, alpha, array)