code: def get_avg_response_time(app_id, from, to)
        url = "#{@base_url}/applications/#{app_id}/metrics/data.json"
        conn = Excon.new(url, persistent: true, tcp_nodelay: true)
        time_range = "from=#{from.iso8601}&to=#{to.iso8601}"
        metric_names_array = %w(
          names[]=HttpDispatcher&values[]=average_call_time&values[]=call_count
          names[]=WebFrontend/QueueTime&values[]=call_count&values[]=average_response_time
        )
        response_array = request(conn, metric_names_array, time_range)
        http_call_count, http_average_call_time = response_array[0]["call_count"], response_array[0]["average_call_time"]
        webfe_call_count, webfe_average_response_time = response_array[1]["call_count"], response_array[1]["average_response_time"]
  
        http_average_call_time + (1.0 * webfe_call_count * webfe_average_response_time / http_call_count) rescue 0.0/0
      end
docs: https://docs.newrelic.com/docs/apis/rest-api-v2/application-examples-v2/average-response-time-examples-v2